JP4158479B2 - Image signal processing apparatus and processing method, coefficient data generating apparatus and generating method used therefor, and program for executing each method - Google Patents

Description

【００５９】
この第１の処理部１２１の動作を説明する。
バッファメモリ１０８に記憶されているＩピクチャの画像信号Ｖａ(I)に基づいて、クラスタップ選択回路１３２で、作成すべきＩピクチャの画像信号Ｖｂ(I)における注目位置に対して空間方向の周辺に位置するクラスタップの画素データが選択的に取り出される。このクラスタップの画素データはクラス生成回路１３３に供給される。このクラス生成回路１３３では、クラスタップの画素データに１ビットのＡＤＲＣ等の処理が施されて、空間クラスを示すクラスコードＣＬ１が生成される。
【００６０】
このクラスコードＣＬ１は、画像信号Ｖｂ(I)における注目位置の画素データが属するクラスの検出結果を表している。このクラスコードＣＬ１は、係数メモリ１３４に読み出しアドレス情報として供給される。この係数メモリ１３４からクラスコードＣＬ１に対応した係数データＷｉが読み出されて、推定予測演算回路１３５に供給される。
【００６１】
また、バッファメモリ１０８に記憶されているＩピクチャの画像信号Ｖａ(I)に基づいて、予測タップ選択回路１３１で、作成すべきＩピクチャの画像信号Ｖｂ(I)における注目位置に対して空間方向の周辺に位置する予測タップの画素データが選択的に取り出される。
【００６２】
推定予測演算回路１３５では、予測タップの画素データｘｉと、係数メモリ１３４より読み出される係数データＷｉとを用いて、上述の（１）式に示す推定式に基づいて、作成すべきＩピクチャの画像信号Ｖｂ(I)における注目位置の画素データｙが求められる。
【００６３】
このように第１の処理部１２１では、Ｉピクチャの画像信号Ｖａ(I)から係数データＷｉを用いてＩピクチャの画像信号Ｖｂ(I)が得られる。この場合、画像信号Ｖａ(I)に基づいて選択された、画像信号Ｖｂ(I)における注目位置の周辺に位置する複数の画素データ（予測タップの画素データ）、およびこの画像信号Ｖｂ(I)における注目位置の画素データが属するクラスＣＬ１に対応した係数データＷｉを用いて、推定式に基づいて画像信号Ｖｂ(I)における注目位置の画素データｙを生成するものである。
【００６４】
したがって、係数データＷｉとして、画像信号Ｖａ(I)に対応しこの画像信号Ｖａ(I)と同様の符号化雑音を含む生徒信号と画像信号Ｖｂ(I)に対応した符号化雑音を含まない教師信号とを用いた学習によって得られた係数データＷｉを用いることで、画像信号Ｖｂ(I)として画像信号Ｖａ(I)に比べて符号化雑音が軽減されたものを得ることができる。
【００６５】
図４は、第２の処理部１２２の構成を示している。この第２の処理部１２２は、予測に使用する予測タップの複数の画素データを選択的に取り出す予測タップ選択回路１４１と、クラス分類に使用するクラスタップの複数の画素データを選択的に取り出すクラスタップ選択回路１４２とを有している。
【００６６】
タップ選択回路１４１，１４２には、システムコントローラ１０１から、ＰピクチャまたはＢピクチャの画像信号Ｖｂ(P)／Ｖｂ(B)における注目位置に対応した画像信号Ｖａ(P)／Ｖａ(B)の画素データと対となっている動き補償用ベクトル情報ＭＩおよびピクチャ情報ＰＩが、動作制御情報として供給される。予測タップおよびクラスタップの画素データは、それぞれ、画像信号Ｖｂ(P)／Ｖｂ(B)における注目位置に対して空間方向（水平方向、垂直方向）および時間方向（フレーム方向）の周辺に位置する画素データである。
【００６７】
タップ選択回路１４１，１４２は、それぞれ、バッファメモリ１０８に格納されているＰピクチャまたはＢピクチャの画像信号Ｖａ(P)／Ｖａ(B)、およびバッファメモリ１２３に格納されている、そのピクチャの画像信号Ｖａ(P)／Ｖａ(B)を得る際に使用されたＩピクチャ、Ｐピクチャの画像信号Ｖａ(I)，Ｖａ(P)に対応した、既に符号化雑音が軽減されたＩピクチャ、Ｐピクチャの画像信号Ｖｂ(I)，Ｖｂ(P)に基づいて、複数の画素データを選択的に取り出す。
【００６８】
ここで、タップ選択回路１４１，１４２は、動き補償用ベクトル情報ＭＩに基づき、画像信号Ｖｂ(I)，Ｖｂ(P)に対して、画像信号Ｖａ(P)／Ｖａ(B)を基準とした動き補償を行う。
【００６９】
図５は、動き補償の一例を示している。この例は、Ｐピクチャの画像信号Ｖｂ(P)における注目位置に対して空間方向および時間方向の周辺に位置する画素データを取り出す場合であって、Ｐピクチャの画像信号Ｖａ(P)およびＩピクチャの画像信号Ｖｂ(I)が、画素データの選択対象である場合を示している。
【００７０】
この場合、画像信号Ｖｂ(I)に対して、画像信号Ｖａ(P)を基準とした動き補償が行われる。ここで、図５に示すように、ベクトル情報ＭＩが（−２，＋１）であったとき、タップ選択回路は、画像信号Ｖａ(P)からｘ₁〜ｘ₁₃の画素データを選択的に取り出し、画像信号Ｖｂ(I)から（−２，＋１）だけずれた位置にあるｘ₁〜ｘ₁₃の画素データを選択的に取り出す。
【００７１】
このように、予測タップ選択回路１４１において、動き補償を行って予測タップの画素データを選択的に取り出すようにしたことで、予測タップの画素データは相関が高いものとなる。そのため、この予測タップの画素データを用いて後述するように生成される画像信号Ｖａ(P)／Ｖａ(B)における注目位置の画素データの品質を高めることができる。
【００７２】
また、クラスタップ選択回路１４２において、動き補償を行ってクラスタップの画素データを選択的に取り出すようにしたことで、上述したように予測タップ選択回路１４１で動き補償が行われて選択された予測タップの画素データに対応した時空間クラスを良好に検出できる。
【００７３】
また、第２の処理部１２２は、クラスタップ選択回路１４２で選択的に取り出されるクラスタップの画素データから時空間クラスを示すクラスコードＣＬ２を生成するクラス生成回路１４３を有している。このクラス生成回路１４３は、上記した第１の処理部１２１のクラス生成回路１３３と同様に、クラスタップの画素データに１ビットのＡＤＲＣ等の処理を施すことによって、空間クラスを示すクラスコードＣＬ２を生成する。
【００７４】
また、第１の処理部１２２は、係数メモリ１４４を有している。この係数メモリ１４４は、後述する推定予測演算回路１４５で使用される推定式で用いられる係数データＷｉ（ｉ＝１〜ｎ、ｎは予測タップの個数）を、クラス毎に、格納するものである。
【００７５】
この係数メモリ１４４には、Ｐピクチャの画像信号Ｖａ(P)をＰピクチャの画像信号Ｖｂ(P)に変換するためのＰピクチャ用の係数データＷｉと、Ｂピクチャの画像信号Ｖａ(B)をＢピクチャの画像信号Ｖｂ(B)に変換するためのＢピクチャ用の係数データＷｉとが別個のアドレスに格納されている。この係数メモリ１４４には、システムコントローラ１０１からピクチャ情報ＰＩが読み出し制御情報として供給される。
【００７６】
この係数メモリ１４４に格納される係数データＷｉは、予め画像信号Ｖａ(P)／Ｖａ(B)に対応した生徒信号と画像信号Ｖｂ(P)／Ｖｂ(B)に対応した教師信号との間の学習によって生成される。この係数メモリ１４４には上述したクラス生成回路１４３で生成されるクラスコードＣＬ２が読み出しアドレス情報として供給される。この係数メモリ１４４からはクラスコードＣＬ２に対応した推定式の係数データＷｉが読み出されて、推定予測演算回路１４５に供給される。係数データＷｉの生成方法については後述する。
【００７７】
また、第２の処理部１２２は、予測タップ選択回路１４１で選択的に取り出される予測タップの画素データｘｉと、係数メモリ１４４より読み出される係数データＷｉとから、上述の（１）式の推定式によって、作成すべき画像信号Ｖｂ(P)／Ｖｂ(B)における注目位置の画素データｙを演算する推定予測演算回路１４５を有している。
【００７８】
この第２の処理部１２２の動作を説明する。
バッファメモリ１０８に格納されているＰピクチャまたはＢピクチャの画像信号Ｖａ(P)／Ｖａ(B)、およびバッファメモリ１２３に格納されているその画像信号Ｖａ(P)／Ｖａ(B)を得る際に使用されたＩピクチャ、Ｐピクチャの画像信号Ｖａ(I)，Ｖａ(P)に対応した、Ｉピクチャ、Ｐピクチャの画像信号Ｖｂ(I)，Ｖｂ(P)に基づいて、クラスタップ選択回路１４２で、作成すべきＰピクチャまたはＢピクチャの画像信号Ｖｂ(P)／Ｖｂ(B)における注目位置に対して空間方向および時間方向の周辺に位置するクラスタップの画素データが選択的に取り出される。この場合、動き補償用ベクトル情報ＭＩに基づき、画像信号Ｖｂ(I)，Ｖｂ(P)に対して、画像信号Ｖａ(P)／Ｖａ(B)を基準とした動き補償が行われる。
【００７９】
クラスタップ選択回路１４２で取り出されるクラスタップの画素データはクラス生成回路１４３に供給される。このクラス生成回路１４３では、クラスタップの画素データに１ビットのＡＤＲＣ等の処理が施されて、時空間クラスを示すクラスコードＣＬ２が生成される。このクラスコードＣＬ２は、画像信号Ｖｂ(P)／Ｖｂ(I)における注目位置の画素データが属するクラスの検出結果を表している。このクラスコードＣＬ２は、係数メモリ１４４に読み出しアドレス情報として供給される。
【００８０】
この係数メモリ１４４からクラスコードＣＬ２に対応した係数データＷｉが読み出されて、推定予測演算回路１４５に供給される。この場合、ピクチャ情報ＰＩに基づいて、Ｐピクチャの画像信号Ｖｂ(P)を作成する場合にはＰピクチャ用の係数データＷｉが読み出され、Ｂピクチャの画像信号Ｖｂ(B)を作成する場合にはＢピクチャ用の係数データＷｉが読み出される。
【００８１】
また、バッファメモリ１０８に格納されているＰピクチャまたはＢピクチャの画像信号Ｖａ(P)／Ｖａ(B)、およびバッファメモリ１２３に格納されているその画像信号Ｖａ(P)／Ｖａ(B)を得る際に使用されたＩピクチャ、Ｐピクチャの画像信号Ｖａ(I)，Ｖａ(P)に対応した、Ｉピクチャ、Ｐピクチャの画像信号Ｖｂ(I)，Ｖｂ(P)に基づいて、予測タップ選択回路１４１で、作成すべきＰピクチャまたはＢピクチャの画像信号Ｖｂ(P)／Ｖｂ(B)における注目位置に対して空間方向および時間方向の周辺に位置する予測タップの画素データが選択的に取り出される。この場合、動き補償用ベクトル情報ＭＩに基づき、画像信号Ｖｂ(I)，Ｖｂ(P)に対して、画像信号Ｖａ(P)／Ｖａ(B)を基準とした動き補償が行われる。
【００８２】
推定予測演算回路１４５では、予測タップの画素データｘｉと、係数メモリ１４４より読み出される係数データＷｉとを用いて、上述の（１）式に示す推定式に基づいて、作成すべきＰピクチャまたはＢピクチャの画像信号Ｖｂ(P)／Ｖｂ(I)における注目位置の画素データｙが求められる。
【００８３】
このように第２の処理部１２２では、ＰピクチャまたはＢピクチャの画像信号Ｖａ(P)／Ｖａ(B)から、係数データＷｉを用いて、ＰピクチャまたはＢピクチャの画像信号Ｖｂ(P)／Ｖｂ(B)が得られる。この場合、画像信号Ｖａ(P)／Ｖａ(B)およびＶｂ(I)、Ｖｂ(P)に基づいて選択された、画像信号Ｖｂ(P)／Ｖｂ(B)における注目位置の周辺に位置する複数の画素データ（予測タップの画素データ）、およびこの画像信号Ｖｂ(P)／Ｖｂ(B)における注目位置の画素データが属するクラスＣＬ２に対応した係数データＷｉを用いて、推定式に基づいて画像信号Ｖｂ(P)／Ｖｂ(B)における注目位置の画素データｙを生成するものである。
【００８４】
したがって、係数データＷｉとして、画像信号Ｖａ(P)／Ｖａ(B)に対応しこの画像信号Ｖａ(P)／Ｖａ(B)と同様の符号化雑音を含む生徒信号と画像信号Ｖｂ(P)／Ｖｂ(B)に対応した符号化雑音を含まない教師信号とを用いた学習によって得られた係数データＷｉを用いることで、画像信号Ｖｂ(P)／Ｖｂ(B)として画像信号Ｖａ(P)／Ｖａ(B)に比べて符号化雑音が軽減されたものを得ることができる。
【００８５】
また、予測タップの画素データは、画像信号Ｖａ(P)／Ｖａ(B)から選択される他に、符号化雑音が軽減された画像信号Ｖｂ(I)、Ｖｂ(P)からも選択されるものであり、画像信号Ｖｂ(P)／Ｖｂ(B)の品質の向上を図ることができ、それらに含まれる符号化雑音を良好に軽減できる。
【００８６】
図１に戻って、また、画像信号処理部１１０は、第１の処理部１２１より出力されるＩピクチャの画像信号Ｖｂ(I)および第２の処理部１２２より出力されるＰピクチャ、Ｂピクチャの画像信号Ｖｂ(P)，Ｖｂ(B)を、実際のフレーム／フィールドの順番に並べ換え、画像信号Ｖｂとして出力する並べ換え部１２４を有している。並べ換え部１２４は、バッファメモリ１２５を利用して並べ換え処理を行う。
【００８７】
画像信号処理部１１０の動作を説明する。
バッファメモリ１０８に格納されている画像信号ＶａのうちＩピクチャの画像信号Ｖａ(I)は第１の処理部１２１に供給される。第１の処理部１２１は、このＩピクチャの画像信号Ｖａ(I)から、係数データＷｉを用いて、符号化雑音を軽減したＩピクチャの画像信号Ｖｂ(I)を生成する。
【００８８】
この場合、画像信号Ｖａ(I)に基づいて選択された、画像信号Ｖｂ(I)における注目位置の周辺に位置する複数の画素データ（予測タップの画素データ）、およびこの画像信号Ｖｂ(I)における注目位置の画素データが属するクラスＣＬ１に対応した係数データＷｉを用いて、推定式に基づいて画像信号Ｖｂ(I)における注目位置の画素データｙを生成する。
【００８９】
第１の処理部１２１で生成されたＩピクチャの画像信号Ｖｂ(I)は、並べ換え部１２４に供給されると共に、バッファメモリ１２３に供給されて一時的に格納される。このようにバッファメモリ１２３に格納されたＩピクチャの画像信号Ｖｂ(I)は、第２の処理部１２２で、Ｐピクチャの画像信号Ｖｂ(P)を生成する際に用いられる。
【００９０】
また、バッファメモリ１０８に格納されている画像信号ＶａのうちＰピクチャまたはＢピクチャの画像信号Ｖａ(P)／Ｖａ(I)は第２の処理部１２２に供給される。第２の処理部１２２は、この画像信号Ｖａ(P)／Ｖａ(B)およびバッファメモリ１２３に格納されているＩピクチャ、Ｐピクチャの画像信号Ｖｂ(I)，Ｖｂ(P)から、係数データＷｉを用いて、符号化雑音を軽減したＰピクチャまたはＢピクチャの画像信号Ｖｂ(P)／Ｖｂ(B)を生成する。
【００９１】
この場合、画像信号Ｖａ(P)／Ｖａ(B)およびＶｂ(I)、Ｖｂ(P)に基づいて選択された、画像信号Ｖｂ(P)／Ｖｂ(B)における注目位置の周辺に位置する複数の画素データ（予測タップの画素データ）、およびこの画像信号Ｖｂ(P)／Ｖｂ(B)における注目位置の画素データが属するクラスＣＬ２に対応した係数データＷｉを用いて、推定式に基づいて画像信号Ｖｂ(P)／Ｖｂ(B)における注目位置の画素データｙを生成する。
【００９２】
第２の処理部１２２で生成されたＰピクチャ、Ｂピクチャの画像信号Ｖｂ(P)，Ｖｂ(B)は、並べ換え部１２４に供給される。また、第２の処理部１２２で生成されたＰピクチャの画像信号Ｖｂ(P)は、バッファメモリ１２３に供給されて一時的に格納される。このようにバッファメモリ１２３に格納されたＰピクチャの画像信号Ｖｂ(I)は、第２の処理部１２２で、Ｂピクチャの画像信号Ｖｂ(B)を生成する際に用いられる。
【００９３】
並べ換え部１２４は、第１の処理部１２１より出力されるＩピクチャの画像信号Ｖｂ(I)および第２の処理部１２２より出力されるＰピクチャ、Ｂピクチャの画像信号Ｖｂ(P)，Ｖｂ(B)を、符号化の順番から実際のフレーム／フィールドの順番に並べ換え、画像信号Ｖｂとして順次出力する。
【００９４】
このように画像信号処理部１１０では、画像信号Ｖａから係数データＷｉを用いて画像信号Ｖｂが得られる。したがって、係数データＷｉとして、画像信号Ｖａに対応しこの画像信号Ｖａと同様の符号化雑音を含む生徒信号と画像信号Ｖｂに対応した符号化雑音を含まない教師信号とを用いた学習によって得られた係数データＷｉを用いることで、画像信号Ｖｂとして画像信号Ｖａに比べて符号化雑音が軽減されたものを得ることができる。
【００９５】
また、Ｐピクチャ、Ｂピクチャの画像信号Ｖｂ(P)，Ｖｂ(B)を得る際に、第２の処理部１２２では、予測タップの画素データを画像信号Ｖａ(P)／Ｖａ(B)から選択する他に、符号化雑音が軽減された画像信号Ｖｂ(I)、Ｖｂ(P)からも選択するものである。したがって、Ｐピクチャ、Ｂピクチャの画像信号Ｖｂ(P)，Ｖｂ(B)の品質の向上を図ることができ、それらに含まれる符号化雑音を良好に軽減できる。
【００９６】
また、第２の処理部１２２では、画像信号Ｖｂ(I)、Ｖｂ(P)に対して画像信号Ｖａ(P)／Ｖａ(B)を基準とした動き補償を行って予測タップの画素データを選択的に取り出すものである。したがって、画像信号Ｖａ(P)／Ｖａ(B)における注目位置の画素データを生成するための予測タップの画素データは相関が高いものとなり、画像信号Ｖｂ(P)／Ｖｂ(B)の品質を高めることができる。
【００９７】
次に、第１の処理部１２１（図３参照）の係数メモリ１３４、第２の処理部１２２（図４参照）の係数メモリ１４４に記憶される係数データＷｉの生成方法について説明する。この係数データＷｉは、予め学習によって生成されたものである。
【００９８】
まず、この学習方法について説明する。上述の、（１）式において、学習前は係数データＷ₁，Ｗ₂，‥‥，Ｗ_nは未定係数である。学習は、クラス毎に、複数の信号データに対して行う。学習データ数がｍの場合、（１）式に従って、以下に示す（２）式が設定される。ｎは予測タップの数を示している。
ｙ_k＝Ｗ₁×ｘ_k1＋Ｗ₂×ｘ_k2＋‥‥＋Ｗ_n×ｘ_kn ・・・（２）
（ｋ＝１，２，‥‥，ｍ）
【００９９】
ｍ＞ｎの場合、係数データＷ₁，Ｗ₂，‥‥，Ｗ_nは、一意に決まらないので、誤差ベクトルｅの要素ｅ_kを、以下の式（３）で定義して、（４）式のｅ²を最小にする係数データを求める。いわゆる最小２乗法によって係数データを一意に定める。
ｅ_k＝ｙ_k−｛Ｗ₁×ｘ_k1＋Ｗ₂×ｘ_k2＋‥‥＋Ｗ_n×ｘ_kn｝ ・・・（３）
（ｋ＝１，２，‥‥ｍ）
【０１００】
【数２】

【０１０１】
（４）式のｅ²を最小とする係数データを求めるための実際的な計算方法としては、まず、（５）式に示すように、ｅ²を係数データＷｉ(ｉ＝１，２，・・・，ｎ）で偏微分し、ｉの各値について偏微分値が０となるように係数データＷｉを求めればよい。
【０１０２】
【数３】

【０１０３】
（５）式から係数データＷｉを求める具体的な手順について説明する。（６）式、（７）式のようにＸji，Ｙiを定義すると、（５）式は、（８）式の行列式の形に書くことができる。
【０１０４】
【数４】

【０１０５】
【数５】

【０１０６】
（８）式は、一般に正規方程式と呼ばれるものである。この正規方程式を掃き出し法（Gauss-Jordanの消去法）等の一般解法で解くことにより、係数データＷｉ（ｉ＝１，２，・・・，ｎ）を求めることができる。
【０１０７】
図６は、第１の処理部１２１の係数メモリ１３４に格納すべき係数データＷｉを生成する係数データ生成装置１５０の構成を示している。
【０１０８】
この係数データ生成装置１５０は、画像信号Ｖｂに対応した教師信号ＳＴが入力される入力端子１５１と、この教師信号ＳＴに対して符号化を行ってＭＰＥＧ２ストリームを得るＭＰＥＧ２符号化器１５２と、このＭＰＥＧ２ストリームに対して復号化を行って画像信号Ｖａに対応した生徒信号ＳＳを得るＭＰＥＧ２復号化器１５３とを有している。ここで、ＭＰＥＧ２復号化器１５３は、図１に示すデジタル放送受信機１００におけるＭＰＥＧ２復号化器１０７およびバッファメモリ１０８に対応したものである。
【０１０９】
また、係数データ生成装置１５０は、復号化器１５３より出力されるＩピクチャの生徒信号ＳＳ(I)に基づいて、予測に使用する予測タップの複数の画素データを選択的に取り出す予測タップ選択回路１５４と、同様に、復号化器１５３より出力されるＩピクチャの生徒信号ＳＳ(I)に基づいて、クラス分類に使用するクラスタップの複数の画素データを選択的に取り出すクラスタップ選択回路１５４とを有している。これらのタップ選択回路１５４，１５５は、第１の処理部１２１のタップ選択回路１３１，１３２と同様に構成される。予測タップおよびクラスタップの画素データは、それぞれ、Ｉピクチャの教師信号ＳＴ(I)における注目位置に対して空間方向（水平方向、垂直方向）の周辺に位置する画素データである。
【０１１０】
また、係数データ生成装置１５０は、クラスタップ選択回路１５４で選択的に取り出されるクラスタップの画素データから空間クラスを示すクラスコードＣＬ１を生成するクラス生成回路１５６を有している。このクラス生成回路１５６は、第１の処理部１２１のクラス生成回路１３３と同様に構成される。
【０１１１】
また、係数データ生成装置１５０は、入力端子１５１に供給される教師信号ＳＴの時間調整を行うための遅延回路１５７と、この遅延回路１５７で時間調整されたＩピクチャの教師信号ＳＴ(I)より得られる各注目位置の画素データｙと、この各注目位置の画素データｙにそれぞれ対応して予測タップ選択回路１５５で選択的に取り出される予測タップの画素データｘｉと、各注目位置の画素データｙにそれぞれ対応してクラス生成回路１５６で生成されるクラスコードＣＬ１とから、クラス毎に、係数データＷｉ（ｉ＝１〜ｎ）を得るための正規方程式（上述の（８）式参照）を生成する正規方程式生成部１５８を有している。
【０１１２】
この場合、１個の画素データｙとそれに対応するｎ個の予測タップの画素データｘｉとの組み合わせで１個の学習データが生成されるが、教師信号ＳＴ(I)と生徒信号ＳＳ(I)との間で、クラス毎に、多くの学習データが生成されていく。これにより、正規方程式生成部１５８では、クラス毎に、係数データＷｉ（ｉ＝１〜ｎ）を得るための正規方程式が生成される。
【０１１３】
また、係数データ生成装置１５０は、正規方程式生成部１５８で生成された正規方程式のデータが供給され、その正規方程式を解いて、各クラスの係数データＷｉを求める係数データ決定部１５９と、この求められた各クラスの係数データＷｉを格納する係数メモリ１６０とを有している。
【０１１４】
次に、図６に示す係数データ生成装置１５０の動作を説明する。
入力端子１５１には画像信号Ｖｂに対応した教師信号ＳＴが供給され、そしてＭＰＥＧ２符号化器１５２で、この教師信号ＳＴに対して符号化が施されて、ＭＰＥＧ２ストリームが生成される。このＭＰＥＧ２ストリームは、ＭＰＥＧ２復号化器１５３に供給される。ＭＰＥＧ２復号化器１５３で、このＭＰＥＧ２ストリームに対して復号化が施されて、画像信号Ｖａに対応した生徒信号ＳＳが生成される。
【０１１５】
復号化器１５３で生成されたＩピクチャの生徒信号ＳＳ(I)に基づいて、クラスタップ選択回路１５５で、Ｉピクチャの教師信号ＳＴ(I)における注目位置に対して空間方向の周辺に位置するクラスタップの画素データが選択的に取り出される。このクラスタップの画素データはクラス生成回路１５６に供給される。このクラス生成回路１５６では、クラスタップの画素データに１ビットのＡＤＲＣ等の処理が施されて、空間クラスを示すクラスコードＣＬ１が生成される。
【０１１６】
また、復号化器１５３で生成されたＩピクチャの生徒信号ＳＳ(I)に基づいて、予測タップ選択回路１５４で、Ｉピクチャの教師信号ＳＴ(I)における注目位置に対して空間方向の周辺に位置する予測タップの画素データが選択的に取り出される。
【０１１７】
そして、遅延回路１５７で時間調整された教師信号ＳＴ(I)から得られる各注目位置の画素データｙと、この各注目位置の画素データｙにそれぞれ対応して予測タップ選択回路１５４で選択的に取り出される予測タップの画素データｘｉと、各注目位置の画素データｙにそれぞれ対応してクラス生成回路１５６で生成されるクラスコードＣＬ１とを用いて、正規方程式生成部１５８では、クラス毎に、係数データＷｉ（ｉ＝１〜ｎ）を得るための正規方程式（（８）式参照）が生成される。この正規方程式は係数データ決定部１５９で解かれて各クラスの係数データＷｉが求められ、その係数データＷｉは係数メモリ１６０に格納される。
【０１１８】
このように、図６に示す係数データ生成装置１５０においては、第１の処理部１２１の係数メモリ１３４に格納される各クラスの係数データＷｉを生成することができる。
【０１１９】
生徒信号ＳＳは、教師信号ＳＴに対して符号化を施してＭＰＥＧ２ストリームを生成し、その後このＭＰＥＧ２ストリームに対して復号化を施して得たものである。したがって、この生徒信号ＳＳは、画像信号Ｖａと同様の符号化雑音を含んだものとなる。そのため、第１の処理部１２１において、画像信号Ｖａ(I)からこの係数データＷｉを用いて得られる画像信号Ｖｂ(I)は、画像信号Ｖａ(I)に比べて符号化雑音が軽減されたものとなる。
【０１２０】
図７は、第２の処理部１２２の係数メモリ１４４に格納すべき係数データＷｉを生成する係数データ生成装置１７０の構成を示している。
この係数データ生成装置１７０は、画像信号Ｖｂに対応した教師信号ＳＴが入力される入力端子１７１と、この教師信号ＳＴを一時的に格納するバッファメモリ１７２とを有している。
【０１２１】
また、係数データ生成装置１７０は、バッファメモリ１７２に一時的に格納さた教師信号ＳＴに対して符号化を行ってＭＰＥＧ２ストリームを得るＭＰＥＧ２符号化器１７３と、このＭＰＥＧ２ストリームに対して復号化を行って画像信号Ｖａに対応した生徒信号ＳＳを得るＭＰＥＧ２復号化器１７４とを有している。ここで、ＭＰＥＧ２復号化器１７４は、図１に示すデジタル放送受信機１００におけるＭＰＥＧ２復号化器１０７およびバッファメモリ１０８に対応したものである。
【０１２２】
また、係数データ生成装置１７０は、予測に使用する予測タップの複数の画素データを選択的に取り出す予測タップ選択回路１７５と、クラス分類に使用するクラスタップの複数の画素データを選択的に取り出すクラスタップ選択回路１７６とを有している。これらのタップ選択回路１７５，１７６は、第２の処理部１２２のタップ選択回路１４１，１４２と同様に構成される。
【０１２３】
タップ選択回路１７５，１７６には、復号化器１７４から、ＰピクチャまたはＢピクチャの教師信号ＳＴ(P)／ＳＴ(B)における注目位置に対応した生徒信号ＳＳ(P)／ＳＳ(I)の画素データと対となっている動き補償用ベクトル情報ＭＩおよびピクチャ情報ＰＩが、動作制御情報として供給される。予測タップおよびクラスタップの画素データは、それぞれ、ＰピクチャまたはＢピクチャの教師信号ＳＴ(P)／ＳＴ(B)における注目位置に対して空間方向（水平方向、垂直方向）および時間方向（フレーム方向）の周辺に位置する画素データである。
【０１２４】
タップ選択回路１７５，１７６は、それぞれ、復号化器１７４で得られるＰピクチャまたはＢピクチャの生徒信号ＳＳ(P)／ＳＳ(B)、およびバッファメモリ１７２に格納されている、そのピクチャの生徒信号ＳＳ(P)／ＳＳ(B)を得る際に使用されたＩピクチャ、Ｐピクチャの生徒信号ＳＳ(I)，ＳＳ(P)に対応した、Ｉピクチャ、Ｐピクチャの教師信号ＳＴ(I)，ＳＴ(P)に基づいて、複数の画素データを選択的に取り出す。
【０１２５】
ここで、タップ選択回路１７５，１７６は、動き補償用ベクトル情報ＭＩに基づき、教師信号ＳＴ(I)，ＳＴ(P)に対して、生徒信号ＳＳ(P)／ＳＳ(B)を基準とした動き補償を行う。
【０１２６】
また、係数データ生成装置１７０は、クラスタップ選択回路１７６で選択的に取り出されるクラスタップの画素データから時空間クラスを示すクラスコードＣＬ２を生成するクラス生成回路１７７を有している。このクラス生成回路１７７は、第２の処理部１２２のクラス生成回路１４３と同様に構成される。
【０１２７】
また、係数データ生成装置１７０は、バッファメモリ１７２より読み出される教師信号ＳＴの時間調整を行うための遅延回路１７８と、この遅延回路１７８で時間調整されたＰピクチャまたはＢピクチャの教師信号ＳＴ(P)／ＳＴ(B)より得られる各注目位置の画素データｙと、この各注目位置の画素データｙにそれぞれ対応して予測タップ選択回路１７５で選択的に取り出される予測タップの画素データｘｉと、各注目位置の画素データｙにそれぞれ対応してクラス生成回路１７７で生成されるクラスコードＣＬ２とから、クラス毎に、係数データＷｉ（ｉ＝１〜ｎ）を得るための正規方程式（上述の（８）式参照）を生成する正規方程式生成部１７９を有している。
【０１２８】
この場合、１個の画素データｙとそれに対応するｎ個の予測タップの画素データｘｉとの組み合わせで１個の学習データが生成されるが、教師信号ＳＴ(P)／ＳＴ(B)と生徒信号ＳＳ(P)／ＳＳ(B)との間で、クラス毎に、多くの学習データが生成されていく。これにより、正規方程式生成部１７９では、クラス毎に、係数データＷｉ（ｉ＝１〜ｎ）を得るための正規方程式が生成される。
【０１２９】
また、係数データ生成装置１７０は、正規方程式生成部１７９で生成された正規方程式のデータが供給され、その正規方程式を解いて、各クラスの係数データＷｉを求める係数データ決定部１８０と、この求められた各クラスの係数データＷｉを格納する係数メモリ１８１とを有している。
【０１３０】
次に、図７に示す係数データ生成装置１７０の動作を説明する。
入力端子１７１には画像信号Ｖｂに対応した教師信号ＳＴが供給され、この教師信号ＳＴはバッファメモリ１７２に一時的に格納される。そして、このようにバッファメモリ１７２に一時的に格納された教師信号ＳＴに対して、ＭＰＥＧ２符号化器１７３で符号化が施されて、ＭＰＥＧ２ストリームが生成される。このＭＰＥＧ２ストリームは、ＭＰＥＧ２復号化器１７４に供給される。ＭＰＥＧ２復号化器１７４で、このＭＰＥＧ２ストリームに対して復号化が施されて、画像信号Ｖａに対応した生徒信号ＳＳが生成される。
【０１３１】
教師信号ＳＴ(P)／ＳＴ(B)の注目位置に対応した生徒信号ＳＳ(P)／ＳＳ(B)の画素データと対となっている動き補償用ベクトル情報ＭＩおよびピクチャ情報ＰＩが、復号化器１７４から予測タップ選択回路１７５およびクラスタップ選択回路１７６に、動作制御情報として供給される。
【０１３２】
復号化器１７４で生成されたＰピクチャまたはＢピクチャの生徒信号ＳＳ(P)／ＳＳ(B)、およびバッファメモリ１７２に格納されている、そのピクチャの生徒信号ＳＳ(P)／ＳＳ(B)を得る際に使用されたＩピクチャ、Ｐピクチャの生徒信号ＳＳ(I)，ＳＳ(P)に対応した、Ｉピクチャ、Ｐピクチャの教師信号ＳＴ(I)，ＳＴ(P)に基づいて、クラスタップ選択回路１７６で、ＰピクチャまたはＢピクチャの教師信号ＳＴ(P)／ＳＴ(B)における注目位置に対して空間方向および時間方向の周辺に位置するクラスタップの画素データが選択的に取り出される。この場合、動き補償用ベクトル情報ＭＩに基づき、教師信号ＳＴ(I)，ＳＴ(P)に対して、生徒信号ＳＳ(P)／ＳＳ(B)を基準とした動き補償が行われる。
【０１３３】
クラスタップ選択回路１７６で選択的に取り出されたクラスタップの画素データはクラス生成回路１７７に供給される。このクラス生成回路１７７では、クラスタップの画素データに１ビットのＡＤＲＣ等の処理が施されて、時空間クラスを示すクラスコードＣＬ２が生成される。
【０１３４】
また、復号化器１７４で生成されたＰピクチャまたはＢピクチャの生徒信号ＳＳ(P)／ＳＳ(B)、およびバッファメモリ１７２に格納されている、そのピクチャの生徒信号ＳＳ(P)／ＳＳ(B)を得る際に使用されたＩピクチャ、Ｐピクチャの生徒信号ＳＳ(I)，ＳＳ(P)に対応した、Ｉピクチャ、Ｐピクチャの教師信号ＳＴ(I)，ＳＴ(P)に基づいて、予測タップ選択回路１７５で、ＰピクチャまたはＢピクチャの教師信号ＳＴ(P)／ＳＴ(B)における注目位置に対して空間方向および時間方向の周辺に位置する予測タップの画素データが選択的に取り出される。この場合、動き補償用ベクトル情報ＭＩに基づき、教師信号ＳＴ(I)，ＳＴ(P)に対して、生徒信号ＳＳ(P)／ＳＳ(B)を基準とした動き補償が行われる。
【０１３５】
そして、遅延回路１７８で時間調整された教師信号ＳＴ(P)／ＳＴ(B)から得られる各注目位置の画素データｙと、この各注目位置の画素データｙにそれぞれ対応して予測タップ選択回路１７５で選択的に取り出される予測タップの画素データｘｉと、各注目位置の画素データｙにそれぞれ対応してクラス生成回路１７７で生成されるクラスコードＣＬ２とを用いて、正規方程式生成部１７９では、クラス毎に、係数データＷｉ（ｉ＝１〜ｎ）を得るための正規方程式（（８）式参照）が生成される。この正規方程式は係数データ決定部１８０で解かれて各クラスの係数データＷｉが求められ、その係数データＷｉは係数メモリ１８１に格納される。
【０１３６】
このように、図７に示す係数データ生成装置１７０においては、第２の処理部１２２の係数メモリ１４４に格納される各クラスの係数データＷｉを生成することができる。
【０１３７】
生徒信号ＳＳは、教師信号ＳＴに対して符号化を施してＭＰＥＧ２ストリームを生成し、その後このＭＰＥＧ２ストリームに対して復号化を施して得たものである。したがって、この生徒信号ＳＳは、画像信号Ｖａと同様の符号化雑音を含んだものとなる。そのため、第２の処理部１２２において、画像信号Ｖａ(P)／Ｖａ(B)等からこの係数データＷｉを用いて得られる画像信号Ｖｂ(P)／Ｖｂ(B)は、画像信号Ｖａ(P)／Ｖａ(B)に比べて符号化雑音が軽減されたものとなる。
【０１３８】
なお、図１の画像信号処理部１１０における処理を、例えば図８に示すような画像信号処理装置３００によって、ソフトウェアで実現することも可能である。
【０１３９】
まず、図１７に示す画像信号処理装置３００について説明する。この画像信号処理装置３００は、装置全体の動作を制御するＣＰＵ３０１と、このＣＰＵ３０１の制御プログラムや係数データ等が格納されたＲＯＭ（Read Only Memory）３０２と、ＣＰＵ３０１の作業領域を構成するＲＡＭ（Random Access Memory）３０３とを有している。これらＣＰＵ３０１、ＲＯＭ３０２およびＲＡＭ３０３は、それぞれバス３０４に接続されている。
【０１４０】
また、画像信号処理装置３００は、外部記憶装置としてのハードディスクドライブ（ＨＤＤ）３０５と、フロッピー（登録商標）ディスク３０６をドライブするドライブ（ＦＤＤ）３０７とを有している。これらドライブ３０５，３０７は、それぞれバス３０４に接続されている。
【０１４１】
また、画像信号処理装置３００は、インターネット等の通信網４００に有線または無線で接続する通信部３０８を有している。この通信部３０８は、インタフェース３０９を介してバス３０４に接続されている。
【０１４２】
また、画像信号処理装置３００は、ユーザインタフェース部を備えている。このユーザインタフェース部は、リモコン送信機２００からのリモコン信号ＲＭを受信するリモコン信号受信回路３１０と、ＬＣＤ（Liquid Crystal Display）等からなるディスプレイ３１１とを有している。受信回路３１０はインタフェース３１２を介してバス３０４に接続され、同様にディスプレイ３１１はインタフェース３１３を介してバス３０４に接続されている。
【０１４３】
また、画像信号処理装置３００は、画像信号Ｖａを入力するための入力端子３１４と、画像信号Ｖｂを出力するための出力端子３１５とを有している。入力端子３１４はインタフェース３１６を介してバス３０４に接続され、同様に出力端子３１５はインタフェース３１７を介してバス３０４に接続される。
【０１４４】
ここで、上述したようにＲＯＭ３０２に制御プログラムや係数データ等を予め格納しておく代わりに、例えばインターネットなどの通信網４００より通信部３０８を介してダウンロードし、ハードディスクやＲＡＭ３０３に蓄積して使用することもできる。また、これら制御プログラムや係数データ等をフロッピー（登録商標）ディスク３０６で提供するようにしてもよい。
【０１４５】
また、処理すべき画像信号Ｖａを入力端子３１４より入力する代わりに、予めハードディスクに記録しておき、あるいはインターネットなどの通信網４００より通信部３０８を介してダウンロードしてもよい。また、処理後の画像信号Ｖｂを出力端子３１５に出力する代わり、あるいはそれと並行してディスプレイ３１１に供給して画像表示をしたり、さらにはハードディスクに格納したり、通信部３０８を介してインターネットなどの通信網４００に送出するようにしてもよい。
【０１４６】
図９のフローチャートを参照して、図８に示す画像信号処理装置３００における、画像信号Ｖａより画像信号Ｖｂを得るため処理手順を説明する。
まず、ステップＳＴ２１で、処理を開始し、ステップＳ２２で、例えば入力端子３１４より装置内に１ＧＯＰ(Group Of Picture)分の画像信号Ｖａを入力する。この場合、画像信号Ｖａの画素データと対となっている動き補償用ベクトル情報ＭＩおよびピクチャ情報ＰＩも入力する。
【０１４７】
このように入力端子３１４より入力される画像信号Ｖａ等はＲＡＭ３０３に一時的に格納される。なお、この画像信号Ｖａ等が装置内のハードディスクドライブ３０５に予め記録されている場合には、このドライブ３０５からこの画像信号Ｖａ等を読み出し、この画像信号Ｖａ等をＲＡＭ３０３に一時的に格納する。
【０１４８】
そして、ステップＳＴ２３で、画像信号Ｖａの全てのＧＯＰの処理が終わっているか否かを判定する。処理が終わっているときは、ステップＳＴ２４で、処理を終了する。一方、処理が終わっていないときは、ステップＳＴ２５に進む。
【０１４９】
このステップＳＴ２５では、ステップＳＴ２２で入力されたＩピクチャの画像信号Ｖａ(I)に基づいて、Ｉピクチャの画像信号Ｖｂ(I)における注目位置に対して空間方向の周辺に位置する複数の画素データ（クラスタップの画素データ）を選択的に取り出し、このクラスタップの画素データを用いてＩピクチャの画像信号Ｖｂ(I)における注目位置の画素データが属するクラスを示すクラスコードＣＬ１を生成する。
【０１５０】
次に、ステップＳＴ２６で、ステップＳＴ２２で入力されたＩピクチャの画像信号Ｖａ(I)に基づいて、Ｉピクチャの画像信号Ｖｂ(I)における注目位置に対して空間方向の周辺に位置する複数の画素データ（予測タップの画素データ）を取得する。そして、ステップＳＴ２７で、ステップＳＴ２５で生成されたクラスコードＣＬ１に対応した係数データＷｉとステップＳＴ２６で取得された予測タップの画素データｘｉを使用して、（１）式の推定式に基づいて、Ｉピクチャの画像信号Ｖｂ(I)における注目位置の画素データｙを生成する。このように生成される画像データからなるＩピクチャの画像信号Ｖｂ(I)は、ＲＡＭ３０３に一時的に格納される。
【０１５１】
そして、ステップＳＴ２８で、Ｉピクチャの処理が終了したか否かを判定する。終了していないときは、ステップＳＴ２５に戻って、次の注目位置についての処理に移る。一方処理が終了しているときは、ステップＳＴ２９に進み、ＰピクチャおよびＢピクチャの画像信号Ｖｂ(P)，Ｖｂ(B)を得る処理に移る。
【０１５２】
これらの画像信号Ｖｂ(P)，Ｖｂ(B)を得る処理は、上述したＩピクチャの画像信号Ｖｂ(I)を得るステップＳＴ２５〜ステップＳＴ２８までの処理と同様に行われる。ただし、予測タップおよびクラスタップの画素データは、ステップＳＴ２２で入力されたＰピクチャ、Ｂピクチャの画像信号Ｖａ(P)，Ｖａ(B)の他に、生成されたＩピクチャ、Ｐピクチャの画像信号Ｖｂ(I)、Ｖｂ(P)からも選択的に取り出される。また、画像信号Ｖａ(P)，Ｖａ(B)を基準として、画像信号Ｖｂ(I)、Ｖｂ(P)に対して、動き補償用ベクトル情報ＭＩに基づいて動き補償が行われる。
【０１５３】
ステップＳＴ２９で、所定のＰピクチャまたはＢピクチャの処理が終了したとき、ステップＳＴ３０で、処理すべき次のピクチャがあるか否かを判定する。次のピクチャがあるときは、ステップＳＴ２９に戻って、そのピクチャの画像信号を得る処理に移る。一方、処理すべき次のピクチャがないときは、ステップＳＴ３１に進む。
【０１５４】
ステップＳＴ３１では、生成された１ＧＯＰ分の画像信号Ｖｂ(I)，Ｖｂ(P)，Ｖｂ(B)を、符号化の順番から、実際のフレーム／フィールドの順番に並べ換えて、出力端子３１５に出力する。そして、その後、ステップＳＴ２２に戻って、次の１ＧＯＰ分の画像信号Ｖａの入力処理に移る。
【０１５５】
このように、図９に示すフローチャートに沿って処理をすることで、入力された画像信号Ｖａの画素データを処理して、画像信号Ｖｂの画素データを得ることができる。上述したように、このように処理して得られた画像信号Ｖｂは出力端子３１５に出力されたり、ディスプレイ３１１に供給されてそれによる画像が表示されたり、さらにはハードディスクドライブ３０５に供給されてハードディスクに記録されたりする。
【０１５６】
また、処理装置の図示は省略するが、図６の係数データ生成装置１５０における処理も、ソフトウェアで実現可能である。
【０１５７】
図１０のフローチャートを参照して、係数データを生成するための処理手順を説明する。
まず、ステップＳＴ３１で、処理を開始し、ステップＳＴ３２で、教師信号ＳＴを１ＧＯＰ分だけ入力する。そして、ステップＳＴ３３で、教師信号ＳＴの全てのＧＯＰの処理が終了したか否かを判定する。終了していないときは、ステップＳＴ３４で、ステップＳＴ３２で入力された教師信号ＳＴから生徒信号ＳＳを生成する。
【０１５８】
次に、ステップＳＴ３５で、ステップＳＴ３４で生成されたＩピクチャの生徒信号ＳＳ(I)に基づいて、Ｉピクチャの教師信号ＳＴ(I)における注目位置に対して空間方向の周辺に位置する複数の画素データ（クラスタップの画素データ）を選択的に取り出し、このクラスタップの画素データを用いてＩピクチャの教師信号ＳＴ(I)における注目位置の画素データが属するクラスを示すクラスコードＣＬ１を生成する。
【０１５９】
次に、ステップＳＴ３６で、ステップＳＴ３４で生成されたＩピクチャの生徒信号ＳＳ(I)に基づいて、Ｉピクチャの教師信号ＳＴ(I)における注目位置に対して空間方向の周辺に位置する複数の画素データ（予測タップの画素データ）を取得する。
【０１６０】
そして、ステップＳＴ３７で、ステップＳＴ３５で生成されたクラスコードＣＬ１、ステップＳＴ３６で取得された予測タップの画素データｘｉおよび教師信号ＳＴ(I)における注目位置の画素データｙを用いて、クラス毎に、（８）式に示す正規方程式を得るための加算をする（（６）式、（７）式参照）。
【０１６１】
次に、ステップＳＴ３８で、ステップＳＴ３２で入力されたＩピクチャの教師信号ＳＴ(I)の画素データの全領域において学習処理が終了したか否かを判定する。学習処理を終了しているときは、ステップＳＴ３２に戻って、次の１ＧＯＰ分の教師信号ＳＴの入力を行って、上述したと同様の処理を繰り返す。一方、学習処理を終了していないときは、ステップＳＴ３５に戻って、次の注目位置についての処理に移る。
【０１６２】
上述したステップＳＴ３３で、処理が終了したときは、ステップＳＴ３９で、上述のステップＳＴ３７の加算処理によって生成された、各クラスの正規方程式を掃き出し法などで解いて、各クラスの係数データＷｉを算出する。そして、ステップＳＴ４０で、各クラスの係数データＷｉをメモリに保存し、その後にステップＳＴ４１で、処理を終了する。
【０１６３】
このように、図１０に示すフローチャートに沿って処理をすることで、図６に示す係数データ生成装置１５０と同様の手法によって、Ｉピクチャに係る各クラスの係数データＷｉを得ることができる。
【０１６４】
なお、詳細説明は省略するが、図７の係数データ生成装置１７０における処理も、上述した図６の係数データ生成装置１５０における処理と同様に、ソフトウェアで実現可能である。
【０１６５】
その場合、Ｉピクチャの教師信号ＳＴ(I)、生徒信号ＳＳ(I)の代わりに、Ｐピクチャの教師信号ＳＴ(P)、生徒信号ＳＳ(P)またはＢピクチャの教師信号ＳＴ(B)、生徒信号ＳＳ(B)が用いられる。また、クラスタップ、予測タップの画素データを得る際には、生徒信号ＳＳ(P)／ＳＳ(B)の他に、この生徒信号ＳＳ(P)／ＳＳ(B)を得る際に使用された生徒信号ＳＳ(I)，ＳＳ(P)に対応した教師信号ＳＴ(I)，ＳＴ(P)も用いられる。これにより、ＰピクチャまたはＢピクチャに係る各クラスの係数データＷｉを得ることができる。
【０１６６】
なお、上述実施の形態においては、ＤＣＴを伴うＭＰＥＧ２ストリームを取り扱うものを示したが、この発明は、その他の符号化されたデジタル画像信号を取り扱うものにも同様に適用することができる。また、ＤＣＴの代わりに、ウォーブレット変換、離散サイン変換などのその他の直交変換を伴う符号化であってもよい。符号化雑音軽減後の画像信号（第２の画像信号）をも用いて、第２の画像信号における注目位置の画素データを生成することで、第２の画像信号の品質の向上を図ることができ、符号化雑音を良好に軽減できる。
【０１６７】
また、上述の図１に示す画像信号処理部１１０の第２の処理部１２２では、ＭＰＥＧ２ストリームより抽出された動き補償用ベクトル情報ＭＩを用いて動き補償を行うものを示したが、画像信号Ｖａから動きベクトル情報を検出し、その検出された動き補償ベクトル情報を用いて動き補償を行うようにしてもよい。
【０１６８】
【発明の効果】
この発明によれば、符号化されたデジタル画像信号を復号化することによって生成される、複数の画素データからなる第１の画像信号を、複数の画素データからなる第２の画像信号に変換して符号化雑音を軽減する際、第１の画像信号の他に、符号化雑音が軽減された第２の画像信号に基づいて第２の画像信号における注目位置に対して時間方向および空間方向の周辺に位置する複数の第１の画素データを選択し、この複数の第１の画素データを用いて第２の画像信号における注目位置の画素データを生成するものであり、第２の画像信号の品質の向上を図ることができ、符号化雑音を良好に軽減できる。
【図面の簡単な説明】
【図１】実施の形態としてのデジタル放送受信機の構成を示すブロック図である。
【図２】ＭＰＥＧ２復号化器の構成を示すブロック図である。
【図３】第１の処理部の構成を示すブロック図である。
【図４】第２の処理部の構成を示すブロック図である。
【図５】動き補償を説明するための図である。
【図６】係数データ生成装置の構成を示すブロック図である。
【図７】係数データ生成装置の構成を示すブロック図である。
【図８】ソフトウェアで実現するための画像信号処理装置の構成例を示すブロック図である。
【図９】画像信号処理を示すフローチャートである。
【図１０】係数データ生成処理を示すフローチャートである。
【符号の説明】
１００・・・デジタル放送受信機、１０１・・・システムコントローラ、１０２・・・リモコン信号受信回路、１０５・・・受信アンテナ、１０６・・・チューナ部、１０７・・・ＭＰＥＧ２復号化器、１０８，１２３，１２５・・・バッファメモリ、１１０・・・画像信号処理部、１１１・・・ディスプレイ部、１２１・・・第１の処理部、１２２・・・第２の処理部、１２４・・・並べ換え部、１３１，１４１・・・予測タップ選択回路、１３２，１４２・・・クラスタップ選択回路、１３３，１４３・・・クラス生成回路、１３４，１４４・・・係数メモリ、１３５，１４５・・・推定予測演算回路、１５０，１７０・・・係数データ生成装置、３００・・・画像信号処理装置[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image signal processing device and processing method, a coefficient data generating device and generating method used therefor, and a program for executing each method.
[0002]
More specifically, the present invention converts a first image signal composed of a plurality of pixel data, which is generated by decoding an encoded digital image signal, into a second image signal composed of a plurality of pixel data. When the coding noise is reduced, the temporal direction and the spatial direction with respect to the target position in the second image signal based on the second image signal in which the coding information is reduced in addition to the first image signal. A plurality of first pixel data located in the vicinity of the second image signal is selected, and pixel data at the position of interest in the second image signal is generated using the plurality of first pixel data. The present invention relates to an image signal processing apparatus or the like that can improve quality and reduce coding noise satisfactorily.
[0003]
[Prior art]
As an image signal compression encoding method, there is an MPEG2 (Moving Picture Experts Group 2) encoding method using DCT (Discrete Cosine Transform). In this encoding method, motion compensation prediction encoding is performed for each block.
[0004]
DCT performs discrete cosine transform on pixels in a block, requantizes coefficient data obtained by the discrete cosine transform, and further variable-length-encodes the requantized coefficient data. For this variable length coding, entropy coding such as Huffman code is often used. The image signal is orthogonally transformed to be divided into a large number of frequency data from low frequency to high frequency.
[0005]
When re-quantization is performed on this divided frequency data, human visual characteristics are taken into consideration, and low frequency data with high importance is finely quantized, and high frequency data with low importance is roughly quantized. By providing the above, it has a feature that high quality is maintained and efficient compression is realized.
[0006]
In conventional decoding using DCT, quantized data for each frequency component is converted into a representative value of the code, and reproduction data is obtained by applying inverse DCT (IDCT: Inverce DCT) to these components. . When converting to this representative value, the quantization step width at the time of encoding is used.
[0007]
[Problems to be solved by the invention]
As described above, the MPEG encoding method using DCT has the advantage that high-quality compression can be realized while maintaining high image quality by performing encoding in consideration of human visual characteristics.
[0008]
However, since coding for performing DCT is processing in units of blocks, block noise, so-called block noise (block distortion), may occur as the compression rate increases. In addition, in a portion where there is a rapid luminance change such as an edge, a noise that is a result of coarse quantization of high-frequency components, so-called mosquito noise, is generated.
[0009]
Such encoding noise is generated not only by the MPEG2 encoding method but also by other encoding methods.
[0010]
An object of the present invention is to satisfactorily reduce coding noise of an image signal obtained by decoding an encoded digital image signal.
[0011]
[Means for Solving the Problems]
An image signal processing apparatus according to the present invention is as follows. The first image signal of the I picture among the first image signals composed of a plurality of pixel data generated by decoding the digital image signal encoded in the MPEG system is converted and encoded. A first processing unit that generates a second image signal of an I picture with reduced distortion caused by encoding, and a conversion process that is performed on a P picture and a B picture of the first image signal to accompany encoding A second processing unit that generates a second image signal of a P picture and a B picture with reduced distortion; a second image signal of an I picture obtained by the first processing unit; and the second processing unit And a memory for storing the second image signal of the P picture obtained in step (1), wherein the first processing unit draws attention from the first image signal of the I picture to the second image signal of the I picture. Around the position A first class detection unit that selects a plurality of pixel data to be generated, generates a class from the level distribution of the selected pixel data, and is obtained in advance for each class detected by the first class detection unit. Coefficient data that minimizes an error between a student signal including coding distortion corresponding to the first image signal of the picture and a teacher signal not including coding distortion corresponding to the second image signal of the I picture; A first prediction for selecting a plurality of pixel data located around a position of interest in the second image signal of the I picture from the first coefficient data generation unit to be generated and the first image signal of the I picture; The coefficient data generated by the tap selection unit, the first coefficient data generation unit, and the plurality of pixel data selected by the first prediction tap selection unit are calculated to obtain the second image signal of the I picture. Oh A first arithmetic unit that obtains pixel data at a target position, and the second processing unit includes a first image signal of the P picture or B picture and an I picture or P picture stored in the memory. A plurality of pieces of pixel data located around the position of interest in the second image signal of the P picture or the B picture are selected from the second image signal, and a class is generated from the level distribution of the selected pixel data. 2 class detection units, a student signal that is obtained in advance for each class detected by the second class detection unit and includes coding distortion corresponding to the first image signal of the P picture or B picture, and the above A second coefficient data generation unit that generates coefficient data that minimizes an error from a teacher signal that does not include coding distortion corresponding to the second image signal of the P picture or B picture, and the P picture or B A plurality of pixels located around the position of interest in the second image signal of the P picture or B picture from the first image signal of the picture and the second image signal of the I picture or P picture stored in the memory A second prediction tap selection unit for selecting data; coefficient data generated by the second coefficient data generation unit; and a plurality of pixel data selected by the second prediction tap selection unit to calculate the P A second calculation unit that obtains pixel data of a target position in a second image signal of a picture or B picture Is.
[0012]
An image signal processing method according to the present invention includes: The first image signal of the I picture among the first image signals composed of a plurality of pixel data generated by decoding the digital image signal encoded in the MPEG system is converted and encoded. A first step of generating a second image signal of an I picture in which distortion caused by encoding is reduced, and distortion caused by encoding by performing conversion processing on a P picture and a B picture of the first image signal The second step of generating the second image signal of the P picture and B picture with reduced I, the second image signal of the I picture obtained in the first step, and the second step obtained in the second step A second step of storing the second image signal of the P picture in a memory, wherein in the first step, the second image signal of the I picture is derived from the first image signal of the I picture. A fourth step of selecting a plurality of pixel data located around the attention position in FIG. 5 and generating a class from the level distribution of the selected pixel data, and a class obtained in advance for each class detected in the fourth step The error between the student signal including coding distortion corresponding to the first image signal of the I picture and the teacher signal not including coding distortion corresponding to the second image signal of the I picture is minimized. A fifth step of generating coefficient data, and a sixth step of selecting a plurality of pixel data located around the position of interest in the second image signal of the I picture from the first image signal of the I picture And a position of interest in the second image signal of the I picture by calculating the coefficient data generated in the fifth step and the plurality of pixel data selected in the sixth step. A seventh step of obtaining pixel data, wherein in the second step, the first image signal of the P picture or B picture and the second image signal of the I picture or P picture stored in the memory An eighth step of selecting a plurality of pixel data located around the position of interest in the second image signal of the P picture or B picture, and generating a class from the level distribution of the selected pixel data; A student signal obtained in advance for each class detected in the eighth step and including a coding distortion corresponding to the first image signal of the P picture or B picture and the second image of the P picture or B picture A ninth step of generating coefficient data that minimizes an error from a teacher signal that does not include coding distortion corresponding to the signal; and a first image signal of the P picture or B picture. And a second image signal of the I picture or P picture stored in the memory, and a plurality of pixel data located around the position of interest in the second image signal of the P picture or B picture are selected. And the pixel data at the target position in the second image signal of the P picture or B picture by calculating the coefficient data generated in the ninth step and the plurality of pixel data selected in the tenth step. An eleventh step of obtaining data Is.
[0013]
A program according to the present invention is for causing a computer to execute the above-described image signal processing method.
[0014]
In the present invention, the first image signal including a plurality of pixel data is generated by decoding the encoded digital image signal. For example, the digital image signal has been subjected to MPEG encoding.
[0015]
Based on the first image signal and the second image signal, a plurality of first pixel data located in the periphery in the time direction and the spatial direction corresponding to the target position in the second image signal are selected. Then, pixel data of the target position in the second image signal is generated using the plurality of first pixel data.
[0016]
For example, when the digital image signal has been subjected to MPEG encoding, a plurality of first pixel data are selected as follows. That is, when the pixel data of the first image signal corresponding to the target position in the second image signal is pixel data related to the I picture, a plurality of first pixel data are selected based on the first image signal. The Further, when the pixel data of the first image signal corresponding to the position of interest in the second image signal is pixel data related to the P picture or B picture, the pixel data of the first image signal and P picture or B picture are A plurality of first pixel data is selected based on the second image signal corresponding to the first image signal used in the acquisition.
[0017]
In this way, pixel data at the position of interest in the second image signal is generated using the plurality of first image data, and it is possible to obtain the second image signal with reduced coding noise. It becomes.
[0018]
For example, based on the first image signal and the second image signal, a plurality of second pixel data located around the time position and the spatial direction with respect to the target position in the second image signal are selected. Based on the plurality of second pixel data, the class to which the pixel data at the target position belongs is detected. Then, using the coefficient data generated corresponding to the detected class and the plurality of first pixel data, the pixel data of the target position in the second image signal is calculated based on the estimation formula.
[0019]
Learning using a student signal corresponding to the first image signal and including the same coding noise as the first image signal and a teacher signal corresponding to the second image signal and not including the coding noise as coefficient data By using the coefficient data obtained by the above, it is possible to obtain a second image signal with reduced coding noise compared to the first image signal.
[0020]
In addition to the first image signal, the plurality of first pixel data is also selected from the second image signal in which the coding noise is reduced, and improves the quality of the second image signal. Therefore, encoding noise can be reduced satisfactorily.
[0021]
Note that motion compensation is performed on the second image signal based on the first image signal, and the second image signal when the plurality of first pixel data is selected is used as the second image signal. These image signals may be used. By performing motion compensation on the second image signal, the plurality of first pixel data selected from the image signals of the respective screens existing in the time direction have high correlation, and the plurality of first pixel data The quality of the pixel data at the target position in the second image signal generated using can be improved.
[0022]
The coefficient data generation device according to the present invention is: The first image signal of the I picture among the first image signals composed of a plurality of pixel data generated by decoding the digital image signal encoded in the MPEG system is converted and encoded. Compatible with the second image signal of I picture with reduced distortion Decoding the digital image signal obtained by encoding the teacher signal I picture A student signal corresponding to the first image signal is obtained. First Decryption Part When, A first class detection unit that selects a plurality of pixel data located around a target position in the teacher signal of the I picture from the student signal of the I picture, and generates a class from the level distribution of the selected pixel data; The first prediction tap selection unit that selects a plurality of pixel data located around the target position in the teacher signal of the I picture from the student signal of the I picture, and the first class detection unit A plurality of pixel data related to the student signal of the I picture and the I picture for each class from the class, the plurality of pixel data selected by the first prediction tap selection unit, and the pixel data of the target position in the teacher signal A first arithmetic unit that obtains coefficient data that minimizes an error from pixel data of a target position in the teacher signal of Distortion accompanying encoding by performing conversion processing on the first image signal of P picture or B picture among the first image signals composed of a plurality of pixel data generated by decoding the digital image signal A student corresponding to the first image signal of the P picture or B picture by decoding the digital image signal obtained by encoding the teacher signal corresponding to the second image signal of the P picture or B picture with reduced P A second decoding unit for obtaining a signal; a memory for storing a teacher signal for the I picture and the P picture; a student signal for the P picture or B picture; and a teacher signal for the I picture or P picture stored in the memory To select a plurality of pixel data located around the position of interest in the teacher signal of the P picture or B picture, and the level of the selected pixel data In the teacher signal of the P picture or B picture, the second class detection unit for generating a class from the cloth, the student signal of the P picture or B picture and the teacher signal of the I picture or P picture stored in the memory A second prediction tap selection unit that selects a plurality of pixel data located around the target position, a class detected by the second class detection unit, and a plurality of selections selected by the second prediction tap selection unit For each class, a plurality of pixel data related to the P picture or B picture student signal and pixel data of the target position in the P picture or B picture teacher signal from the pixel data and the pixel data of the target position in the teacher signal A second arithmetic unit for obtaining coefficient data that minimizes the error of With Ru Is.
[0023]
The coefficient data generation method according to the present invention includes: The first image signal of the I picture among the first image signals composed of a plurality of pixel data generated by decoding the digital image signal encoded in the MPEG system is converted and encoded. Compatible with the second image signal of I picture with reduced distortion Decoding the digital image signal obtained by encoding the teacher signal I picture A student signal corresponding to the first image signal is obtained. First step When, A second step of selecting a plurality of pixel data located around a target position in the teacher signal of the I picture from the student signal of the I picture, and generating a class from the level distribution of the selected pixel data; A third step of selecting a plurality of pixel data located around a target position in the teacher signal of the I picture from the student signal of the I picture, the class detected in the second step, and the third step A plurality of pixel data related to the student signal of the I picture and pixel data of the target position in the teacher signal of the I picture, for each class, from the plurality of pixel data selected in the above and the pixel data of the target position in the teacher signal A fourth step for obtaining coefficient data that minimizes the error of the image and decoding the digital image signal encoded in the MPEG system A P picture or a P picture in which distortion caused by encoding is reduced by performing a conversion process on the first image signal of a P picture or a B picture among the first image signals composed of a plurality of pixel data generated by A fifth image signal is obtained by decoding a digital image signal obtained by encoding a teacher signal corresponding to a second image signal of a B picture to obtain a student signal corresponding to the first image signal of the P picture or B picture. A step of storing a teacher signal of the I picture and the P picture in a memory; a student signal of the P picture or a B picture; and a teacher signal of the I picture or the P picture stored in the memory; Select a plurality of pixel data located around the target position in the teacher signal of P picture or B picture, and whether the level distribution of the selected pixel data The seventh step of generating a class, and the vicinity of the target position in the teacher signal of the P picture or B picture from the student signal of the P picture or B picture and the teacher signal of the I picture or P picture stored in the memory An eighth step of selecting a plurality of pixel data located in the position, a class detected in the seventh step, a plurality of pixel data selected in the eighth step, and a pixel data of a target position in the teacher signal For each class, coefficient data that minimizes an error between a plurality of pixel data related to the student signal of the P picture or B picture and the pixel data of the target position in the teacher signal of the P picture or B picture is obtained. Steps and With Ru Is.
[0024]
A program according to the present invention is for causing a computer to execute the coefficient data generation method described above.
[0025]
In the present invention, the first image signal including a plurality of pixel data is generated by decoding the encoded digital image signal. The present invention generates coefficient data of an estimation formula used when converting the first image signal into a second image signal composed of a plurality of pixel data.
[0026]
The digital image signal obtained by encoding the teacher signal corresponding to the second image signal is further decoded to obtain the student signal corresponding to the first image signal. Based on the student signal and the teacher signal, a plurality of pixel data located in the periphery in the time direction and the spatial direction with respect to the target position in the teacher signal are selected. Then, coefficient data is obtained using the plurality of pixel data and the pixel data of the target position in the teacher signal.
[0027]
As described above, coefficient data of the estimation formula used when converting the first image signal to the second image signal is generated. When converting from the first image signal to the second image signal, The pixel data at the position of interest in the second image signal is calculated by the estimation formula using the coefficient data. Thereby, when converting from the first image signal to the second image signal using the estimation formula, the encoding noise of the image signal obtained by decoding the encoded digital image signal is reduced well. become able to.
[0028]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows a configuration of a digital broadcast receiver 100 as an embodiment.
[0029]
The digital broadcast receiver 100 includes a microcomputer, and includes a system controller 101 for controlling the operation of the entire system, and a remote control signal receiving circuit 102 for receiving a remote control signal RM. The remote control signal receiving circuit 102 is connected to the system controller 101, receives a remote control signal RM output from the remote control transmitter 200 according to a user operation, and supplies an operation signal corresponding to the signal RM to the system controller 101. Is configured to do.
[0030]
Also, the digital broadcast receiver 100 is supplied with a receiving antenna 105 and a broadcast signal (RF modulated signal) captured by the receiving antenna 105, performs channel selection processing, demodulation processing, error correction processing, etc. And a tuner unit 106 that obtains an MPEG2 stream as an encoded image signal.
[0031]
The digital broadcast receiver 100 also temporarily decodes the MPEG2 decoder 107 that decodes the MPEG2 stream output from the tuner unit 106 to obtain the image signal Va, and the image signal Va output from the MPEG2 decoder 107. A buffer memory 108 for storing the data.
[0032]
In the present embodiment, the MPEG2 decoder 107 outputs picture information PI and motion compensation vector information MI in addition to the pixel data constituting the image signal Va. The buffer memory 108 also stores information PI and MI in pairs with each pixel data.
[0033]
The picture information PI is information indicating whether the output pixel data relates to an I picture (Intra-Picture), a P picture (Predictive-Picture), or a B picture (Bidirectionally predictive-Picture). The motion compensation vector information MI is information indicating how the reference image signal at the time of decoding the pixel data is motion compensated when the output pixel data relates to a P picture and a B picture. .
[0034]
FIG. 2 shows the configuration of the MPEG2 decoder 107.
The decoder 107 has an input terminal 71 to which an MPEG2 stream is input, and a stream buffer 72 that temporarily stores the MPEG2 stream input to the input terminal 71.
[0035]
The decoder 107 extracts the DCT (Discrete Cosine Transform) coefficient as a frequency coefficient from the MPEG2 stream stored in the stream buffer 72 and the extraction circuit 73 extracts the DCT coefficient. A variable-length decoding circuit 74 that performs variable-length decoding on DCT coefficients that have been subjected to variable-length coding, for example, Huffman coding.
[0036]
The decoder 107 also includes an extraction circuit 75 that extracts quantization characteristic designation information QI from the MPEG2 stream stored in the stream buffer 72, and a variable length decoding circuit based on the quantization characteristic designation information QI. 74 has an inverse quantization circuit 76 that performs inverse quantization on the quantized DCT coefficient output from 74, and an inverse DCT circuit 77 that performs inverse DCT on the DCT coefficient output from the inverse quantization circuit 76. is doing.
[0037]
In addition, the decoder 107 stores the image signals of the I picture and the P picture in a memory (not shown), and uses these image signals to generate a differential picture signal of the P picture or B picture from the inverse DCT circuit 77. A prediction memory circuit 78 that generates and outputs a corresponding reference image signal Vref when output is provided.
[0038]
In addition, when the inverse picture signal of P picture or B picture is output from the inverse DCT circuit 77, the decoder 107 adds the reference picture signal Vref generated by the prediction memory circuit 78 to the difference picture signal. 79 and an output terminal 81 for outputting an image signal Va of each picture output from the adder circuit 79.
[0039]
Note that when the image signal of the I picture is output from the inverse DCT circuit 77, the reference image signal Vref is not supplied from the prediction memory circuit 78 to the adder circuit 79, and accordingly, is output from the adder circuit 79 from the inverse DCT circuit 77. The image signal of the I picture is output as it is.
[0040]
Here, in MPEG encoding, encoding is performed in an order different from the actual frame / field order, as is conventionally known. That is, the image signal of the I picture and the P picture is encoded first, and the image signal of the B picture sandwiched between them is encoded thereafter. The image signal Va of each picture is output to the output terminal 81 in the encoding order.
[0041]
In addition, the decoder 107 extracts the encoding control information, that is, the picture information PI and the motion compensation vector information MI from the MPEG2 stream stored in the stream buffer 72, and the information PI and MI. And an output terminal 83 for outputting.
[0042]
The motion compensation vector information MI extracted by the extraction circuit 82 is supplied to the prediction memory circuit 78. The prediction memory circuit 78 performs motion compensation when generating the reference image signal Vref using the motion compensation vector information MI. Done. The picture information PI extracted by the extraction circuit 82 is also supplied to the prediction memory circuit 78. The prediction memory circuit 78 identifies a picture based on the picture information PI.
[0043]
The operation of the MPEG2 decoder 107 shown in FIG. 2 will be described.
The MPEG2 stream stored in the stream buffer 72 is supplied to the extraction circuit 73 to extract DCT coefficients as frequency coefficients. This DCT coefficient is variable length encoded, and this DCT coefficient is supplied to the variable length decoding circuit 74 and decoded. The quantized DCT coefficient of each DCT block output from the variable length decoding circuit 74 is supplied to the inverse quantization circuit 76 and subjected to inverse quantization.
[0044]
The inverse DCT circuit 77 performs inverse DCT on the DCT coefficient of each DCT block output from the inverse quantization circuit 76, thereby obtaining an image signal of each picture. The image signal of each picture is output to the output terminal 81 via the adding circuit 79. In this case, when a differential picture signal of P picture or B picture is output from the inverse DCT circuit 77, the reference picture signal Vref output from the prediction memory circuit 78 is added by the adding circuit 79.
[0045]
Note that the motion compensation vector information MI and the picture information PI are output to the output terminal 83 in pairs with the pixel data constituting the image signal Va output from the output terminal 81.
[0046]
Returning to FIG. 1, the digital broadcast receiver 100 also reduces coding noise (coding distortion) such as block noise (block distortion) and mosquito noise from the image signal Va stored in the buffer memory 108. The image signal processing unit 110 that converts the image signal Vb into the image signal Vb and the display unit 111 that displays an image based on the image signal Vb output from the image signal processing unit 110 are provided. The display unit 111 includes a display such as a CRT (Cathode-Ray Tube) display or an LCD (Liquid Crystal Display).
[0047]
The operation of the digital broadcast receiver 100 shown in FIG. 1 will be described.
[0048]
The MPEG2 stream output from the tuner unit 106 is supplied to the MPEG2 decoder 107 and decoded. The image signal Va output from the decoder 107 is supplied to the buffer memory 108 and temporarily stored. In this case, the decoder 107 also outputs motion compensation vector information MI and picture information PI in pairs with each pixel data of the image signal Va. These pieces of information MI and PI are also temporarily stored in the buffer memory 108.
[0049]
Thus, the image signal Va stored in the buffer memory 108 is supplied to the image signal processing unit 110 and converted into the image signal Vb in which the encoding noise (encoding distortion) is reduced. In the image signal processing unit 110, pixel data constituting the image signal Vb is obtained from the pixel data constituting the image signal Va. In the image signal processing unit 110, conversion processing is performed using the motion compensation vector information MI and the picture information PI stored in the buffer memory 108.
[0050]
The image signal Vb output from the image signal processing unit 110 is supplied to the display unit 111, and an image based on the image signal Vb is displayed on the screen of the display unit 111.
[0051]
Next, details of the image signal processing unit 110 will be described.
The image signal processing unit 110 includes a first processing unit 121 that performs conversion processing on an I-picture image signal among the image signals Va stored in the buffer memory 108, and an image signal stored in the buffer memory 108. A second processing unit 122 that performs conversion processing on a P picture and a B picture of Va, an image signal Vb (I) of an I picture obtained by the first processing unit 121, and a second processing unit 122 And a buffer memory 123 that temporarily stores the image signal Vb (P) of the obtained P picture. FIG. 3 for explaining the details of the first processing unit 121 and the second processing unit 122 shows the configuration of the first processing unit 121. The first processing unit 121 includes a prediction tap selection circuit 131 and a class tap selection circuit 132. The prediction tap selection circuit 131 selectively extracts a plurality of pixel data of prediction taps used for prediction based on the image signal Va (I) of the I picture stored in the buffer memory 108. The class tap selection circuit 132 selectively extracts a plurality of pixel data of class taps used for class classification based on the I picture image signal Va (I) stored in the buffer memory 108.
[0052]
The pixel data of the prediction tap and the class tap are pixel data located around the spatial direction (horizontal direction and vertical direction) with respect to the target position in the image signal Vb (I) of the I picture, respectively.
[0053]
The first processing unit 121 includes a class generation circuit 133 that generates a class code CL1 indicating a space class from the pixel data of the class tap selectively extracted by the class tap selection circuit 132. The class generation circuit 133 generates a class code CL1 indicating a space class by performing processing such as 1-bit ADRC (Adaptive Dynamic Range Coding) on the pixel data of the class tap.
[0054]
ADRC calculates the maximum value and minimum value of a plurality of pixel data of a class tap, calculates a dynamic range that is the difference between the maximum value and the minimum value, and requantizes each pixel value in accordance with the dynamic range. . In the case of 1-bit ADRC, the pixel value is converted to 1 bit depending on whether it is larger or smaller than the average value of the plurality of pixel values of the class tap. The ADRC process is a process for making the number of classes representing the level distribution of pixel values relatively small. Therefore, not limited to ADRC, encoding that compresses the number of bits of a pixel value such as VQ (vector quantization) may be used.
[0055]
The first processing unit 121 has a coefficient memory 134. The coefficient memory 134 stores coefficient data Wi (i = 1 to n, n is the number of prediction taps) used for an estimation formula used in an estimation prediction calculation circuit 135 described later for each class. .
[0056]
The coefficient data Wi is information for converting the image signal Va (I) into the image signal Vb (I). The coefficient data Wi stored in the coefficient memory 134 is generated in advance by learning between a student signal corresponding to the image signal Va (I) and a teacher signal corresponding to the image signal Vb (I). The coefficient memory 134 is supplied with the class code CL1 generated by the class generation circuit 133 described above as read address information. Coefficient data Wi of the estimation formula corresponding to the class code CL 1 is read from the coefficient memory 134 and supplied to the estimated prediction calculation circuit 135. A method for generating the coefficient data Wi will be described later.
[0057]
In addition, the first processing unit 121 uses the estimation equation (1) from the prediction tap pixel data xi selectively extracted by the prediction tap selection circuit 131 and the coefficient data Wi read from the coefficient memory 134. It has an estimated prediction calculation circuit 135 for calculating pixel data y at the position of interest in the image signal Vb (I) to be created.
[0058]
[Expression 1]

[0059]
The operation of the first processing unit 121 will be described.
Based on the image signal Va (I) of the I picture stored in the buffer memory 108, the class tap selection circuit 132 performs a peripheral in the spatial direction with respect to the target position in the image signal Vb (I) of the I picture to be created. The pixel data of the class tap located at is selectively extracted. The pixel data of the class tap is supplied to the class generation circuit 133. In this class generation circuit 133, processing such as 1-bit ADRC is performed on the pixel data of the class tap, and a class code CL1 indicating the space class is generated.
[0060]
This class code CL1 represents the detection result of the class to which the pixel data at the target position in the image signal Vb (I) belongs. The class code CL1 is supplied to the coefficient memory 134 as read address information. The coefficient data Wi corresponding to the class code CL1 is read from the coefficient memory 134 and supplied to the estimated prediction calculation circuit 135.
[0061]
Further, based on the image signal Va (I) of the I picture stored in the buffer memory 108, the prediction tap selection circuit 131 performs a spatial direction with respect to the target position in the image signal Vb (I) of the I picture to be created. The pixel data of the prediction tap located in the vicinity of is selectively extracted.
[0062]
The estimated prediction calculation circuit 135 uses the pixel data xi of the prediction tap and the coefficient data Wi read from the coefficient memory 134, and based on the estimation expression shown in the above equation (1), the image of the I picture to be created Pixel data y at the target position in the signal Vb (I) is obtained.
[0063]
As described above, the first processing unit 121 obtains the I-picture image signal Vb (I) from the I-picture image signal Va (I) using the coefficient data Wi. In this case, a plurality of pixel data (prediction tap pixel data) located around the target position in the image signal Vb (I), selected based on the image signal Va (I), and the image signal Vb (I). The pixel data y of the target position in the image signal Vb (I) is generated based on the estimation formula using the coefficient data Wi corresponding to the class CL1 to which the pixel data of the target position in FIG.
[0064]
Accordingly, the coefficient data Wi corresponds to the image signal Va (I) and includes a student signal including encoding noise similar to the image signal Va (I) and a teacher not including encoding noise corresponding to the image signal Vb (I). By using the coefficient data Wi obtained by learning using the signal, it is possible to obtain the image signal Vb (I) with reduced coding noise compared to the image signal Va (I).
[0065]
FIG. 4 shows the configuration of the second processing unit 122. The second processing unit 122 includes a prediction tap selection circuit 141 that selectively extracts a plurality of pixel data of prediction taps used for prediction, and a class that selectively extracts a plurality of pixel data of class taps used for class classification. And a tap selection circuit 142.
[0066]
The tap selection circuits 141 and 142 are supplied from the system controller 101 with pixels of the image signals Va (P) / Va (B) corresponding to the positions of interest in the image signals Vb (P) / Vb (B) of the P picture or B picture. Motion compensation vector information MI and picture information PI paired with the data are supplied as motion control information. The pixel data of the prediction tap and the class tap are located around the spatial direction (horizontal direction, vertical direction) and the temporal direction (frame direction) with respect to the target position in the image signals Vb (P) / Vb (B), respectively. Pixel data.
[0067]
The tap selection circuits 141 and 142 are respectively the P picture or B picture image signal Va (P) / Va (B) stored in the buffer memory 108 and the picture image stored in the buffer memory 123. I picture used for obtaining the signals Va (P) / Va (B), I picture corresponding to the picture signals Va (I), Va (P) of the P picture, P picture already reduced in coding noise, P A plurality of pixel data are selectively extracted based on the picture signals Vb (I) and Vb (P) of the picture.
[0068]
Here, the tap selection circuits 141 and 142 are based on the image signal Va (P) / Va (B) with respect to the image signals Vb (I) and Vb (P) based on the motion compensation vector information MI. Perform motion compensation.
[0069]
FIG. 5 shows an example of motion compensation. This example is a case where pixel data located in the spatial direction and the temporal direction are extracted from the target position in the P-picture image signal Vb (P), and the P-picture image signal Va (P) and I-picture are extracted. The image signal Vb (I) is a pixel data selection target.
[0070]
In this case, motion compensation based on the image signal Va (P) is performed on the image signal Vb (I). Here, as shown in FIG. 5, when the vector information MI is (−2, +1), the tap selection circuit uses the image signal Va (P) to x ₁ ~ X ₁₃ Pixel data is selectively extracted and x at a position shifted by (−2, +1) from the image signal Vb (I). ₁ ~ X ₁₃ Are selectively extracted.
[0071]
As described above, the prediction tap selection circuit 141 performs motion compensation to selectively extract the pixel data of the prediction tap, so that the pixel data of the prediction tap has a high correlation. Therefore, the quality of the pixel data at the target position in the image signals Va (P) / Va (B) generated as described later using the pixel data of the prediction tap can be improved.
[0072]
In addition, since the class tap selection circuit 142 performs motion compensation to selectively extract pixel data of the class tap, the prediction selected by performing the motion compensation in the prediction tap selection circuit 141 as described above. The spatiotemporal class corresponding to the pixel data of the tap can be detected well.
[0073]
In addition, the second processing unit 122 includes a class generation circuit 143 that generates a class code CL2 indicating a spatiotemporal class from the pixel data of the class tap selectively extracted by the class tap selection circuit 142. Similar to the class generation circuit 133 of the first processing unit 121 described above, the class generation circuit 143 performs a process such as 1-bit ADRC on the pixel data of the class tap to generate a class code CL2 indicating the space class. Generate.
[0074]
The first processing unit 122 has a coefficient memory 144. The coefficient memory 144 stores coefficient data Wi (i = 1 to n, where n is the number of prediction taps) used in an estimation formula used in the estimation prediction calculation circuit 145 described later for each class. .
[0075]
In this coefficient memory 144, coefficient data Wi for P picture for converting the image signal Va (P) of the P picture into the image signal Vb (P) of the P picture and the image signal Va (B) of the B picture are stored. B picture coefficient data Wi for conversion into the B picture image signal Vb (B) is stored in a separate address. The coefficient memory 144 is supplied with picture information PI from the system controller 101 as read control information.
[0076]
The coefficient data Wi stored in the coefficient memory 144 is obtained in advance between a student signal corresponding to the image signal Va (P) / Va (B) and a teacher signal corresponding to the image signal Vb (P) / Vb (B). Generated by learning. The coefficient memory 144 is supplied with the class code CL2 generated by the class generation circuit 143 described above as read address information. Coefficient data Wi of the estimation formula corresponding to the class code CL2 is read from the coefficient memory 144 and supplied to the estimated prediction calculation circuit 145. A method for generating the coefficient data Wi will be described later.
[0077]
Further, the second processing unit 122 uses the prediction tap pixel circuit xi selectively extracted by the prediction tap selection circuit 141 and the coefficient data Wi read from the coefficient memory 144 to estimate the above equation (1). Thus, an estimated prediction calculation circuit 145 that calculates pixel data y at the target position in the image signals Vb (P) / Vb (B) to be generated is provided.
[0078]
The operation of the second processing unit 122 will be described.
When obtaining the image signal Va (P) / Va (B) of the P picture or B picture stored in the buffer memory 108 and the image signal Va (P) / Va (B) stored in the buffer memory 123 Class tap selection circuit based on I picture and P picture image signals Vb (I) and Vb (P) corresponding to I picture and P picture image signals Va (I) and Va (P) In 142, pixel data of class taps located in the periphery in the spatial direction and the temporal direction with respect to the target position in the image signal Vb (P) / Vb (B) of the P picture or B picture to be created is selectively extracted. . In this case, motion compensation based on the image signals Va (P) / Va (B) is performed on the image signals Vb (I) and Vb (P) based on the motion compensation vector information MI.
[0079]
The pixel data of the class tap extracted by the class tap selection circuit 142 is supplied to the class generation circuit 143. In the class generation circuit 143, processing such as 1-bit ADRC is performed on the pixel data of the class tap, and a class code CL2 indicating a spatiotemporal class is generated. This class code CL2 represents the detection result of the class to which the pixel data of the target position in the image signal Vb (P) / Vb (I) belongs. The class code CL2 is supplied to the coefficient memory 144 as read address information.
[0080]
The coefficient data Wi corresponding to the class code CL2 is read from the coefficient memory 144 and supplied to the estimated prediction calculation circuit 145. In this case, when the P picture image signal Vb (P) is created based on the picture information PI, the P picture coefficient data Wi is read out and the B picture image signal Vb (B) is created. The coefficient data Wi for B picture is read out.
[0081]
Further, the P picture or B picture image signal Va (P) / Va (B) stored in the buffer memory 108 and the image signal Va (P) / Va (B) stored in the buffer memory 123 are used. Prediction tap based on image signals Vb (I) and Vb (P) of I picture and P picture corresponding to the image signals Va (I) and Va (P) of I picture and P picture used for obtaining The selection circuit 141 selectively selects pixel data of prediction taps located in the periphery in the spatial direction and the temporal direction with respect to the target position in the image signal Vb (P) / Vb (B) of the P picture or B picture to be created. It is taken out. In this case, motion compensation based on the image signals Va (P) / Va (B) is performed on the image signals Vb (I) and Vb (P) based on the motion compensation vector information MI.
[0082]
The estimated prediction calculation circuit 145 uses the prediction tap pixel data xi and the coefficient data Wi read from the coefficient memory 144 to generate a P picture or B to be created based on the estimation expression shown in the above equation (1). Pixel data y at the target position in the picture signal Vb (P) / Vb (I) of the picture is obtained.
[0083]
As described above, the second processing unit 122 uses the coefficient data Wi from the image signal Va (P) / Va (B) of the P picture or B picture, and the image signal Vb (P) / V of the P picture or B picture. Vb (B) is obtained. In this case, it is located around the position of interest in the image signals Vb (P) / Vb (B) selected based on the image signals Va (P) / Va (B) and Vb (I), Vb (P). A plurality of pixel data (prediction tap pixel data) and coefficient data Wi corresponding to the class CL2 to which the pixel data of the target position in the image signals Vb (P) / Vb (B) belongs, and based on the estimation formula Pixel data y at the target position in the image signal Vb (P) / Vb (B) is generated.
[0084]
Accordingly, as the coefficient data Wi, the student signal and the image signal Vb (P) corresponding to the image signal Va (P) / Va (B) and containing the same coding noise as the image signal Va (P) / Va (B). By using coefficient data Wi obtained by learning using a teacher signal that does not include coding noise corresponding to / Vb (B), the image signal Va (P) is obtained as the image signal Vb (P) / Vb (B). ) / Va (B) can be obtained with reduced coding noise.
[0085]
Further, the pixel data of the prediction tap is selected not only from the image signal Va (P) / Va (B) but also from the image signals Vb (I) and Vb (P) with reduced coding noise. Therefore, the quality of the image signals Vb (P) / Vb (B) can be improved, and the encoding noise included in them can be reduced well.
[0086]
Returning to FIG. 1, the image signal processing unit 110 also includes the I picture image signal Vb (I) output from the first processing unit 121 and the P picture and B picture output from the second processing unit 122. The image signal Vb (P) and Vb (B) are rearranged in the actual frame / field order, and the image signal Vb is output as the image signal Vb. The rearrangement unit 124 performs rearrangement processing using the buffer memory 125.
[0087]
The operation of the image signal processing unit 110 will be described.
Of the image signal Va stored in the buffer memory 108, the I-picture image signal Va (I) is supplied to the first processing unit 121. The first processing unit 121 generates an I-picture image signal Vb (I) with reduced coding noise from the I-picture image signal Va (I) using the coefficient data Wi.
[0088]
In this case, a plurality of pixel data (prediction tap pixel data) located around the target position in the image signal Vb (I), selected based on the image signal Va (I), and the image signal Vb (I). The pixel data y of the target position in the image signal Vb (I) is generated based on the estimation formula using the coefficient data Wi corresponding to the class CL1 to which the pixel data of the target position in FIG.
[0089]
The image signal Vb (I) of the I picture generated by the first processing unit 121 is supplied to the rearrangement unit 124 and also supplied to the buffer memory 123 to be temporarily stored. The image signal Vb (I) of the I picture stored in the buffer memory 123 is used when the second processing unit 122 generates the image signal Vb (P) of the P picture.
[0090]
In addition, the image signal Va (P) / Va (I) of the P picture or the B picture among the image signals Va stored in the buffer memory 108 is supplied to the second processing unit 122. The second processing unit 122 generates coefficient data from the image signals Va (P) / Va (B) and the I-picture and P-picture image signals Vb (I) and Vb (P) stored in the buffer memory 123. Using Wi, an image signal Vb (P) / Vb (B) of P picture or B picture with reduced coding noise is generated.
[0091]
In this case, it is located around the position of interest in the image signals Vb (P) / Vb (B) selected based on the image signals Va (P) / Va (B) and Vb (I), Vb (P). A plurality of pixel data (prediction tap pixel data) and coefficient data Wi corresponding to the class CL2 to which the pixel data of the target position in the image signals Vb (P) / Vb (B) belongs, and based on the estimation formula Pixel data y at the target position in the image signal Vb (P) / Vb (B) is generated.
[0092]
The P picture and B picture image signals Vb (P) and Vb (B) generated by the second processing unit 122 are supplied to the rearrangement unit 124. Further, the image signal Vb (P) of the P picture generated by the second processing unit 122 is supplied to the buffer memory 123 and temporarily stored. The image signal Vb (I) of the P picture stored in the buffer memory 123 in this way is used when the second processing unit 122 generates the image signal Vb (B) of the B picture.
[0093]
The rearrangement unit 124 outputs the I-picture image signal Vb (I) output from the first processing unit 121 and the P-picture and B-picture image signals Vb (P) and Vb ( B) is rearranged from the encoding order to the actual frame / field order, and sequentially output as an image signal Vb.
[0094]
As described above, the image signal processing unit 110 obtains the image signal Vb from the image signal Va using the coefficient data Wi. Therefore, the coefficient data Wi is obtained by learning using a student signal corresponding to the image signal Va and including coding noise similar to the image signal Va and a teacher signal corresponding to the image signal Vb and not including coding noise. By using the obtained coefficient data Wi, it is possible to obtain the image signal Vb with reduced coding noise compared to the image signal Va.
[0095]
Further, when obtaining the image signals Vb (P) and Vb (B) of the P picture and the B picture, the second processing unit 122 obtains the pixel data of the prediction tap from the image signals Va (P) / Va (B). In addition to selection, selection is also made from image signals Vb (I) and Vb (P) with reduced coding noise. Therefore, the quality of the image signals Vb (P) and Vb (B) of the P picture and B picture can be improved, and the encoding noise included in them can be reduced well.
[0096]
Further, the second processing unit 122 performs motion compensation on the basis of the image signals Va (P) / Va (B) on the image signals Vb (I) and Vb (P) to obtain pixel data of the prediction tap. Selective extraction. Therefore, the pixel data of the prediction tap for generating the pixel data of the target position in the image signal Va (P) / Va (B) has high correlation, and the quality of the image signal Vb (P) / Vb (B) is improved. Can be increased.
[0097]
Next, a method for generating coefficient data Wi stored in the coefficient memory 134 of the first processing unit 121 (see FIG. 3) and the coefficient memory 144 of the second processing unit 122 (see FIG. 4) will be described. The coefficient data Wi is generated in advance by learning.
[0098]
First, this learning method will be described. In the above equation (1), before learning, coefficient data W ₁ , W ₂ , ..., W _n Is an undetermined coefficient. Learning is performed on a plurality of signal data for each class. When the number of learning data is m, the following equation (2) is set according to the equation (1). n indicates the number of prediction taps.
y _k = W ₁ X _k1 + W ₂ X _k2 + ... + W _n X _kn ... (2)
(K = 1, 2,..., M)
[0099]
If m> n, coefficient data W ₁ , W ₂ , ..., W _n Is not uniquely determined, so the element e of the error vector e _k Is defined by the following equation (3), and e in equation (4) ² Find coefficient data that minimizes. Coefficient data is uniquely determined by a so-called least square method.
e _k = Y _k -{W ₁ X _k1 + W ₂ X _k2 + ... + W _n X _kn } (3)
(K = 1, 2, ... m)
[0100]
[Expression 2]

[0101]
E in equation (4) ² As a practical calculation method for obtaining coefficient data that minimizes the value, first, as shown in equation (5), e ² Is partially differentiated with the coefficient data Wi (i = 1, 2,..., N), and the coefficient data Wi may be obtained so that the partial differential value becomes 0 for each value of i.
[0102]
[Equation 3]

[0103]
A specific procedure for obtaining the coefficient data Wi from the equation (5) will be described. If Xji and Yi are defined as in the equations (6) and (7), the equation (5) can be written in the form of the determinant of the equation (8).
[0104]
[Expression 4]

[0105]
[Equation 5]

[0106]
Equation (8) is generally called a normal equation. Coefficient data Wi (i = 1, 2,..., N) can be obtained by solving this normal equation by a general solution method such as a sweep-out method (Gauss-Jordan elimination method).
[0107]
FIG. 6 shows a configuration of a coefficient data generation device 150 that generates coefficient data Wi to be stored in the coefficient memory 134 of the first processing unit 121.
[0108]
The coefficient data generation device 150 includes an input terminal 151 to which a teacher signal ST corresponding to the image signal Vb is input, an MPEG2 encoder 152 that encodes the teacher signal ST to obtain an MPEG2 stream, An MPEG2 decoder 153 that decodes the MPEG2 stream to obtain a student signal SS corresponding to the image signal Va. Here, the MPEG2 decoder 153 corresponds to the MPEG2 decoder 107 and the buffer memory 108 in the digital broadcast receiver 100 shown in FIG.
[0109]
Also, the coefficient data generation device 150 selectively extracts a plurality of pixel data of prediction taps used for prediction based on the student signal SS (I) of the I picture output from the decoder 153. Similarly, a class tap selection circuit 154 that selectively extracts a plurality of pixel data of class taps used for class classification based on the student signal SS (I) of the I picture output from the decoder 153, and have. These tap selection circuits 154 and 155 are configured in the same manner as the tap selection circuits 131 and 132 of the first processing unit 121. The pixel data of the prediction tap and the class tap are pixel data located around the spatial direction (horizontal direction and vertical direction) with respect to the target position in the teacher signal ST (I) of the I picture.
[0110]
The coefficient data generation device 150 includes a class generation circuit 156 that generates a class code CL1 indicating a space class from the class tap pixel data selectively extracted by the class tap selection circuit 154. The class generation circuit 156 is configured in the same manner as the class generation circuit 133 of the first processing unit 121.
[0111]
Further, the coefficient data generation device 150 uses a delay circuit 157 for adjusting the time of the teacher signal ST supplied to the input terminal 151, and an I picture teacher signal ST (I) adjusted in time by the delay circuit 157. The pixel data y of each target position obtained, the pixel data xi of the prediction tap selectively extracted by the prediction tap selection circuit 155 in correspondence with the pixel data y of each target position, and the pixel data y of each target position A normal equation (see equation (8) above) for generating coefficient data Wi (i = 1 to n) is generated for each class from the class code CL1 generated by the class generation circuit 156 corresponding to each A normal equation generation unit 158 for
[0112]
In this case, one piece of learning data is generated by a combination of one piece of pixel data y and pixel data xi of n prediction taps corresponding thereto, but the teacher signal ST (I) and the student signal SS (I) A lot of learning data is generated for each class. As a result, the normal equation generation unit 158 generates a normal equation for obtaining coefficient data Wi (i = 1 to n) for each class.
[0113]
The coefficient data generation device 150 is supplied with the data of the normal equation generated by the normal equation generation unit 158, solves the normal equation, and obtains the coefficient data Wi of each class, and the coefficient data determination unit 159. And a coefficient memory 160 for storing the obtained coefficient data Wi of each class.
[0114]
Next, the operation of the coefficient data generation device 150 shown in FIG. 6 will be described.
A teacher signal ST corresponding to the image signal Vb is supplied to the input terminal 151, and the MPEG2 encoder 152 encodes the teacher signal ST to generate an MPEG2 stream. This MPEG2 stream is supplied to the MPEG2 decoder 153. The MPEG2 decoder 153 decodes the MPEG2 stream to generate a student signal SS corresponding to the image signal Va.
[0115]
Based on the student signal SS (I) of the I picture generated by the decoder 153, the class tap selection circuit 155 is positioned around the position of interest in the teacher signal ST (I) of the I picture in the spatial direction. The pixel data of the class tap is selectively extracted. The pixel data of this class tap is supplied to the class generation circuit 156. In this class generation circuit 156, processing such as 1-bit ADRC is performed on the pixel data of the class tap, and a class code CL1 indicating the space class is generated.
[0116]
Further, based on the student signal SS (I) of the I picture generated by the decoder 153, the prediction tap selection circuit 154 moves the spatial position around the target position in the teacher signal ST (I) of the I picture. Pixel data of the prediction tap that is located is selectively extracted.
[0117]
Then, the pixel data y of each target position obtained from the teacher signal ST (I) time-adjusted by the delay circuit 157 and the prediction tap selection circuit 154 selectively corresponding to the pixel data y of each target position. The normal equation generation unit 158 uses a coefficient for each class by using the pixel data xi of the prediction tap to be extracted and the class code CL1 generated by the class generation circuit 156 corresponding to the pixel data y of each target position. A normal equation (see equation (8)) for obtaining data Wi (i = 1 to n) is generated. This normal equation is solved by the coefficient data determination unit 159 to obtain the coefficient data Wi of each class, and the coefficient data Wi is stored in the coefficient memory 160.
[0118]
As described above, in the coefficient data generation device 150 illustrated in FIG. 6, the coefficient data Wi of each class stored in the coefficient memory 134 of the first processing unit 121 can be generated.
[0119]
The student signal SS is obtained by encoding the teacher signal ST to generate an MPEG2 stream and then decoding the MPEG2 stream. Therefore, the student signal SS includes the same coding noise as the image signal Va. Therefore, in the first processing unit 121, the encoding noise of the image signal Vb (I) obtained from the image signal Va (I) using the coefficient data Wi is reduced compared to the image signal Va (I). It will be a thing.
[0120]
FIG. 7 shows a configuration of the coefficient data generation device 170 that generates coefficient data Wi to be stored in the coefficient memory 144 of the second processing unit 122.
The coefficient data generation device 170 includes an input terminal 171 to which a teacher signal ST corresponding to the image signal Vb is input, and a buffer memory 172 that temporarily stores the teacher signal ST.
[0121]
The coefficient data generation apparatus 170 encodes the teacher signal ST temporarily stored in the buffer memory 172 to obtain an MPEG2 stream, and decodes the MPEG2 stream. And an MPEG2 decoder 174 for obtaining a student signal SS corresponding to the image signal Va. Here, the MPEG2 decoder 174 corresponds to the MPEG2 decoder 107 and the buffer memory 108 in the digital broadcast receiver 100 shown in FIG.
[0122]
The coefficient data generation device 170 also includes a prediction tap selection circuit 175 that selectively extracts a plurality of pixel data of prediction taps used for prediction, and a class that selectively extracts a plurality of pixel data of class taps used for class classification. And a tap selection circuit 176. These tap selection circuits 175 and 176 are configured in the same manner as the tap selection circuits 141 and 142 of the second processing unit 122.
[0123]
The tap selection circuits 175 and 176 receive the student signals SS (P) / SS (I) from the decoder 174 corresponding to the positions of interest in the teacher signals ST (P) / ST (B) of the P picture or B picture. Motion compensation vector information MI and picture information PI paired with pixel data are supplied as operation control information. The pixel data of the prediction tap and the class tap are respectively in the spatial direction (horizontal direction and vertical direction) and the temporal direction (frame direction) with respect to the target position in the teacher signal ST (P) / ST (B) of the P picture or B picture. ) Is pixel data located in the vicinity.
[0124]
The tap selection circuits 175 and 176 respectively receive the student signal SS (P) / SS (B) of the P picture or B picture obtained by the decoder 174 and the student signal of the picture stored in the buffer memory 172. Teacher signals ST (I), I and P pictures corresponding to the student signals SS (I) and SS (P) of the I picture and P picture used to obtain SS (P) / SS (B) A plurality of pixel data are selectively extracted based on ST (P).
[0125]
Here, the tap selection circuits 175 and 176 are based on the student signals SS (P) / SS (B) with respect to the teacher signals ST (I) and ST (P) based on the motion compensation vector information MI. Perform motion compensation.
[0126]
Further, the coefficient data generation device 170 includes a class generation circuit 177 that generates a class code CL2 indicating a spatiotemporal class from the pixel data of the class tap selectively extracted by the class tap selection circuit 176. The class generation circuit 177 is configured in the same manner as the class generation circuit 143 of the second processing unit 122.
[0127]
The coefficient data generating apparatus 170 also includes a delay circuit 178 for adjusting the time of the teacher signal ST read from the buffer memory 172, and a teacher signal ST (P for a P picture or B picture that has been adjusted by the delay circuit 178. ) / ST (B) pixel data y at each position of interest, and pixel data xi of the prediction tap selectively extracted by the prediction tap selection circuit 175 in correspondence with the pixel data y at each position of interest, A normal equation for obtaining coefficient data Wi (i = 1 to n) for each class from the class code CL2 generated by the class generation circuit 177 corresponding to each pixel data y at each target position (described above ( 8) has a normal equation generation unit 179 that generates (see equation).
[0128]
In this case, one piece of learning data is generated by a combination of one piece of pixel data y and pixel data xi of n prediction taps corresponding thereto, but teacher signals ST (P) / ST (B) and students A lot of learning data is generated for each class between the signals SS (P) / SS (B). As a result, the normal equation generation unit 179 generates a normal equation for obtaining coefficient data Wi (i = 1 to n) for each class.
[0129]
The coefficient data generation device 170 is supplied with the data of the normal equation generated by the normal equation generation unit 179, solves the normal equation, and obtains the coefficient data Wi of each class, and the coefficient data determination unit 180. And a coefficient memory 181 for storing the coefficient data Wi of each class.
[0130]
Next, the operation of the coefficient data generation apparatus 170 shown in FIG. 7 will be described.
A teacher signal ST corresponding to the image signal Vb is supplied to the input terminal 171, and this teacher signal ST is temporarily stored in the buffer memory 172. The teacher signal ST temporarily stored in the buffer memory 172 is encoded by the MPEG2 encoder 173 to generate an MPEG2 stream. This MPEG2 stream is supplied to the MPEG2 decoder 174. The MPEG2 decoder 174 decodes the MPEG2 stream to generate a student signal SS corresponding to the image signal Va.
[0131]
Motion compensation vector information MI and picture information PI paired with pixel data of the student signal SS (P) / SS (B) corresponding to the target position of the teacher signal ST (P) / ST (B) are decoded. The controller 174 supplies the prediction tap selection circuit 175 and the class tap selection circuit 176 as operation control information.
[0132]
The student signal SS (P) / SS (B) of the P picture or B picture generated by the decoder 174 and the student signal SS (P) / SS (B) of the picture stored in the buffer memory 172 Class based on the teacher signals ST (I) and ST (P) of the I picture and P picture corresponding to the student signals SS (I) and SS (P) of the I picture and P picture used when obtaining The tap selection circuit 176 selectively extracts pixel data of class taps located around the spatial direction and the temporal direction with respect to the target position in the teacher signal ST (P) / ST (B) of the P picture or B picture. . In this case, based on the motion compensation vector information MI, motion compensation is performed on the teacher signals ST (I) and ST (P) with reference to the student signals SS (P) / SS (B).
[0133]
The pixel data of the class tap selectively extracted by the class tap selection circuit 176 is supplied to the class generation circuit 177. In the class generation circuit 177, processing such as 1-bit ADRC is performed on the pixel data of the class tap, and a class code CL2 indicating a spatiotemporal class is generated.
[0134]
Further, the student signal SS (P) / SS (B) of the P picture or B picture generated by the decoder 174 and the student signal SS (P) / SS (of the picture stored in the buffer memory 172 Based on the teacher signals ST (I) and ST (P) of the I picture and P picture corresponding to the student signals SS (I) and SS (P) of I picture and P picture used when obtaining B) The prediction tap selection circuit 175 selectively selects pixel data of prediction taps located in the spatial direction and the temporal direction around the target position in the teacher signal ST (P) / ST (B) of the P picture or B picture. It is taken out. In this case, based on the motion compensation vector information MI, motion compensation is performed on the teacher signals ST (I) and ST (P) with reference to the student signals SS (P) / SS (B).
[0135]
Then, the pixel data y of each target position obtained from the teacher signals ST (P) / ST (B) time-adjusted by the delay circuit 178, and the prediction tap selection circuit corresponding to the pixel data y of each target position, respectively. The normal equation generation unit 179 uses the prediction tap pixel data xi selectively extracted in 175 and the class code CL2 generated by the class generation circuit 177 corresponding to the pixel data y of each target position. For each class, a normal equation (see equation (8)) for generating coefficient data Wi (i = 1 to n) is generated. This normal equation is solved by the coefficient data determination unit 180 to obtain the coefficient data Wi of each class, and the coefficient data Wi is stored in the coefficient memory 181.
[0136]
As described above, in the coefficient data generation apparatus 170 illustrated in FIG. 7, the coefficient data Wi of each class stored in the coefficient memory 144 of the second processing unit 122 can be generated.
[0137]
The student signal SS is obtained by encoding the teacher signal ST to generate an MPEG2 stream and then decoding the MPEG2 stream. Therefore, the student signal SS includes the same coding noise as the image signal Va. Therefore, the image signal Vb (P) / Vb (B) obtained by using the coefficient data Wi from the image signal Va (P) / Va (B) or the like in the second processing unit 122 is the image signal Va (P ) / Va (B), the coding noise is reduced.
[0138]
Note that the processing in the image signal processing unit 110 in FIG. 1 can be realized by software, for example, by an image signal processing apparatus 300 as shown in FIG.
[0139]
First, the image signal processing apparatus 300 shown in FIG. 17 will be described. The image signal processing apparatus 300 includes a CPU 301 that controls the operation of the entire apparatus, a ROM (Read Only Memory) 302 that stores a control program of the CPU 301, coefficient data, and the like, and a RAM (Random) that constitutes a work area of the CPU 301. Access Memory) 303. These CPU 301, ROM 302, and RAM 303 are each connected to a bus 304.
[0140]
The image signal processing apparatus 300 also includes a hard disk drive (HDD) 305 as an external storage device and a drive (FDD) 307 that drives a floppy (registered trademark) disk 306. These drives 305 and 307 are each connected to a bus 304.
[0141]
In addition, the image signal processing apparatus 300 includes a communication unit 308 that is connected to a communication network 400 such as the Internet by wire or wirelessly. The communication unit 308 is connected to the bus 304 via the interface 309.
[0142]
In addition, the image signal processing device 300 includes a user interface unit. The user interface unit includes a remote control signal receiving circuit 310 that receives a remote control signal RM from the remote control transmitter 200, and a display 311 that includes an LCD (Liquid Crystal Display) or the like. The receiving circuit 310 is connected to the bus 304 via the interface 312, and similarly the display 311 is connected to the bus 304 via the interface 313.
[0143]
Further, the image signal processing apparatus 300 has an input terminal 314 for inputting the image signal Va and an output terminal 315 for outputting the image signal Vb. The input terminal 314 is connected to the bus 304 via the interface 316, and similarly, the output terminal 315 is connected to the bus 304 via the interface 317.
[0144]
Here, instead of storing the control program and coefficient data in the ROM 302 in advance as described above, for example, they are downloaded from the communication network 400 such as the Internet via the communication unit 308 and stored in the hard disk or RAM 303 for use. You can also. These control programs, coefficient data, and the like may be provided on a floppy (registered trademark) disk 306.
[0145]
Further, instead of inputting the image signal Va to be processed from the input terminal 314, it may be recorded in advance on a hard disk or downloaded from the communication network 400 such as the Internet via the communication unit 308. Further, instead of outputting the processed image signal Vb to the output terminal 315 or in parallel therewith, it is supplied to the display 311 to display an image, further stored in a hard disk, the Internet via the communication unit 308, etc. It may be sent to the communication network 400.
[0146]
A processing procedure for obtaining the image signal Vb from the image signal Va in the image signal processing apparatus 300 shown in FIG. 8 will be described with reference to the flowchart of FIG.
First, in step ST21, processing is started, and in step S22, for example, an image signal Va for 1 GOP (Group Of Picture) is input into the apparatus from the input terminal 314. In this case, motion compensation vector information MI and picture information PI paired with the pixel data of the image signal Va are also input.
[0147]
Thus, the image signal Va and the like input from the input terminal 314 are temporarily stored in the RAM 303. When the image signal Va or the like is recorded in advance in the hard disk drive 305 in the apparatus, the image signal Va or the like is read from the drive 305 and the image signal Va or the like is temporarily stored in the RAM 303.
[0148]
In step ST23, it is determined whether or not all GOPs of the image signal Va have been processed. When the process is finished, the process ends in step ST24. On the other hand, when the process is not finished, the process proceeds to step ST25.
[0149]
In this step ST25, based on the image signal Va (I) of the I picture input in step ST22, a plurality of pixel data located in the periphery in the spatial direction with respect to the target position in the image signal Vb (I) of the I picture (Class tap pixel data) is selectively extracted, and a class code CL1 indicating the class to which the pixel data of the target position in the image signal Vb (I) of the I picture belongs is generated using the class tap pixel data.
[0150]
Next, in step ST26, based on the image signal Va (I) of the I picture input in step ST22, a plurality of positions positioned in the spatial direction around the target position in the image signal Vb (I) of the I picture. Pixel data (pixel data of prediction tap) is acquired. Then, in step ST27, using the coefficient data Wi corresponding to the class code CL1 generated in step ST25 and the pixel data xi of the prediction tap acquired in step ST26, based on the estimation formula of formula (1), Pixel data y at the target position in the image signal Vb (I) of the I picture is generated. The image signal Vb (I) of the I picture composed of the image data generated in this way is temporarily stored in the RAM 303.
[0151]
In step ST28, it is determined whether or not the processing of the I picture has been completed. If not completed, the process returns to step ST25 to move to the process for the next target position. On the other hand, when the process is completed, the process proceeds to step ST29, and the process proceeds to a process of obtaining image signals Vb (P) and Vb (B) of P picture and B picture.
[0152]
The processing for obtaining these image signals Vb (P) and Vb (B) is performed in the same manner as the processing from step ST25 to step ST28 for obtaining the image signal Vb (I) of the I picture described above. However, the pixel data of the prediction tap and the class tap include the generated I picture and P picture image signals in addition to the P picture and B picture image signals Va (P) and Va (B) input in step ST22. It is also selectively extracted from Vb (I) and Vb (P). Also, motion compensation is performed on the image signals Vb (I) and Vb (P) based on the motion compensation vector information MI with the image signals Va (P) and Va (B) as a reference.
[0153]
When processing of a predetermined P picture or B picture is completed in step ST29, it is determined in step ST30 whether there is a next picture to be processed. If there is a next picture, the process returns to step ST29 to shift to a process for obtaining an image signal of the picture. On the other hand, when there is no next picture to be processed, the process proceeds to step ST31.
[0154]
In step ST31, the generated image signals Vb (I), Vb (P), and Vb (B) for 1 GOP are rearranged from the encoding order to the actual frame / field order and output to the output terminal 315. To do. Thereafter, the process returns to step ST22, and the process proceeds to input processing of the image signal Va for the next 1 GOP.
[0155]
In this way, by performing processing according to the flowchart shown in FIG. 9, the pixel data of the input image signal Va can be processed to obtain the pixel data of the image signal Vb. As described above, the image signal Vb obtained by such processing is output to the output terminal 315, supplied to the display 311 to display an image, and further supplied to the hard disk drive 305 to be supplied to the hard disk. Or is recorded.
[0156]
Further, although illustration of the processing device is omitted, the processing in the coefficient data generation device 150 in FIG. 6 can also be realized by software.
[0157]
A processing procedure for generating coefficient data will be described with reference to the flowchart of FIG.
First, in step ST31, the process is started, and in step ST32, the teacher signal ST is input by 1 GOP. In step ST33, it is determined whether or not all GOPs of the teacher signal ST have been processed. If not finished, in step ST34, the student signal SS is generated from the teacher signal ST input in step ST32.
[0158]
Next, in step ST35, based on the student signal SS (I) of the I picture generated in step ST34, a plurality of positions positioned in the spatial direction around the target position in the teacher signal ST (I) of the I picture. Pixel data (class tap pixel data) is selectively extracted, and a class code CL1 indicating a class to which the pixel data at the target position in the I-picture teacher signal ST (I) belongs is generated using the class tap pixel data. .
[0159]
Next, in step ST36, based on the student signal SS (I) of the I picture generated in step ST34, a plurality of positions located in the spatial direction around the target position in the teacher signal ST (I) of the I picture. Pixel data (pixel data of prediction tap) is acquired.
[0160]
In step ST37, the class code CL1 generated in step ST35, the pixel data xi of the prediction tap acquired in step ST36, and the pixel data y of the target position in the teacher signal ST (I) are used for each class. Addition is performed to obtain the normal equation shown in equation (8) (see equations (6) and (7)).
[0161]
Next, in step ST38, it is determined whether or not the learning process has been completed in the entire area of the pixel data of the teacher signal ST (I) of the I picture input in step ST32. When the learning process is finished, the process returns to step ST32, the next 1 GOP of teacher signal ST is input, and the same process as described above is repeated. On the other hand, when the learning process is not finished, the process returns to step ST35 and moves to the process for the next attention position.
[0162]
When the process is completed in step ST33 described above, in step ST39, the normal equation of each class generated by the addition process in step ST37 described above is solved by a sweeping method or the like to calculate the coefficient data Wi of each class. To do. In step ST40, the coefficient data Wi of each class is stored in the memory, and then the process ends in step ST41.
[0163]
As described above, by performing processing according to the flowchart shown in FIG. 10, the coefficient data Wi of each class related to the I picture can be obtained by the same method as the coefficient data generation device 150 shown in FIG.
[0164]
Although detailed description is omitted, the processing in the coefficient data generation device 170 in FIG. 7 can also be realized by software in the same manner as the processing in the coefficient data generation device 150 in FIG. 6 described above.
[0165]
In this case, instead of the I-picture teacher signal ST (I) and the student signal SS (I), the P-picture teacher signal ST (P), the student signal SS (P), or the B-picture teacher signal ST (B), A student signal SS (B) is used. Also, when obtaining pixel data of class taps and prediction taps, it was used to obtain the student signals SS (P) / SS (B) in addition to the student signals SS (P) / SS (B). Teacher signals ST (I) and ST (P) corresponding to the student signals SS (I) and SS (P) are also used. Thereby, the coefficient data Wi of each class related to the P picture or B picture can be obtained.
[0166]
In the above-described embodiment, an MPEG2 stream with DCT is shown. However, the present invention can be similarly applied to other types that handle encoded digital image signals. Further, instead of DCT, encoding with other orthogonal transforms such as a wavelet transform and a discrete sine transform may be used. The quality of the second image signal can be improved by generating pixel data at the position of interest in the second image signal also using the image signal after reducing the coding noise (second image signal). Encoding noise can be reduced satisfactorily.
[0167]
In the second processing unit 122 of the image signal processing unit 110 shown in FIG. 1 described above, motion compensation is performed using the motion compensation vector information MI extracted from the MPEG2 stream. Alternatively, motion vector information may be detected from the motion vector, and motion compensation may be performed using the detected motion compensation vector information.
[0168]
【The invention's effect】
According to the present invention, the first image signal composed of a plurality of pixel data generated by decoding the encoded digital image signal is converted into the second image signal composed of the plurality of pixel data. When the coding noise is reduced by using the second image signal in which the coding noise is reduced in addition to the first image signal, the temporal position and the spatial direction with respect to the target position in the second image signal are reduced. A plurality of first pixel data located in the periphery is selected, and pixel data of a target position in the second image signal is generated using the plurality of first pixel data. Quality can be improved and coding noise can be reduced well.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of a digital broadcast receiver as an embodiment.
FIG. 2 is a block diagram showing a configuration of an MPEG2 decoder.
FIG. 3 is a block diagram illustrating a configuration of a first processing unit.
FIG. 4 is a block diagram showing a configuration of a second processing unit.
FIG. 5 is a diagram for explaining motion compensation.
FIG. 6 is a block diagram illustrating a configuration of a coefficient data generation device.
FIG. 7 is a block diagram illustrating a configuration of a coefficient data generation device.
FIG. 8 is a block diagram illustrating a configuration example of an image signal processing device to be realized by software.
FIG. 9 is a flowchart showing image signal processing.
FIG. 10 is a flowchart showing coefficient data generation processing.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 100 ... Digital broadcast receiver, 101 ... System controller, 102 ... Remote control signal receiving circuit, 105 ... Receiving antenna, 106 ... Tuner part, 107 ... MPEG2 decoder, 108, 123, 125: Buffer memory, 110: Image signal processing unit, 111: Display unit, 121: First processing unit, 122: Second processing unit, 124: Rearrangement 131, 141 ... Predictive tap selection circuit, 132, 142 ... Class tap selection circuit, 133, 143 ... Class generation circuit, 134, 144 ... Coefficient memory, 135, 145 ... Estimation Prediction operation circuit, 150, 170 ... coefficient data generation device, 300 ... image signal processing device

Claims (8)

The first image signal of the I picture among the first image signals composed of a plurality of pixel data generated by decoding the digital image signal encoded in the MPEG system is converted and encoded. A first processing unit for generating a second image signal of an I picture with reduced distortion caused by the conversion to
A second processing unit that generates a second image signal of the P picture and the B picture by performing transformation processing on the P picture and the B picture in the first image signal to reduce distortion caused by encoding;
A memory for storing the second image signal of the I picture obtained by the first processing unit and the second image signal of the P picture obtained by the second processing unit;
The first processing unit includes:
A plurality of pixel data located around the target position in the second image signal of the I picture are selected from the first image signal of the I picture, and a class is generated from the level distribution of the selected pixel data 1 class detector;
Corresponding to a student signal including coding distortion corresponding to the first image signal of the I picture and a second image signal of the I picture, which is obtained in advance for each class detected by the first class detection unit. A first coefficient data generation unit that generates coefficient data that minimizes an error from a teacher signal that does not include coding distortion;
A first prediction tap selection unit that selects, from the first image signal of the I picture, a plurality of pixel data located around the position of interest in the second image signal of the I picture;
Pixel data of the target position in the second image signal of the I picture by calculating the coefficient data generated by the first coefficient data generation unit and the plurality of pixel data selected by the first prediction tap selection unit A first arithmetic unit for obtaining
The second processing unit includes:
From the first image signal of the P picture or B picture and the second image signal of the I picture or P picture stored in the memory, around the position of interest in the second image signal of the P picture or B picture A second class detection unit that selects a plurality of pixel data positioned and generates a class from the level distribution of the selected pixel data;
A student signal which is obtained in advance for each class detected by the second class detection unit and includes coding distortion corresponding to the first image signal of the P picture or B picture and the first of the P picture or B picture. A second coefficient data generation unit that generates coefficient data that minimizes an error from a teacher signal that does not include encoding distortion corresponding to the image signal of 2;
From the first image signal of the P picture or B picture and the second image signal of the I picture or P picture stored in the memory, around the position of interest in the second image signal of the P picture or B picture A second prediction tap selection unit that selects a plurality of pixel data located;
The position of interest in the second image signal of the P picture or B picture by calculating the coefficient data generated by the second coefficient data generation unit and the plurality of pixel data selected by the second prediction tap selection unit And a second arithmetic unit that obtains the pixel data . The second class detection unit and the second prediction tap selection unit include pixel data of the first image signal of the P picture or B picture corresponding to the position of interest in the second image signal of the P picture or B picture, A pair of motion compensation vector information and picture information is supplied, and pixel data of a second image signal of an I picture or P picture stored in the memory is selected based on the motion compensation vector information. Item 2. The image signal processing device according to Item 1.   The second image signal of I picture output from the first processing unit and the second image signal of P picture or B picture output from the second processing unit are rearranged in the order of frames or fields. The image signal processing apparatus according to claim 1, further comprising a rearrangement unit that outputs the third image signal. The first image signal of the I picture among the first image signals composed of a plurality of pixel data generated by decoding the digital image signal encoded in the MPEG system is converted and encoded. A first step of generating a second image signal of an I picture with reduced distortion associated with
A second step of generating a second image signal of the P picture and the B picture by performing transformation processing on the P picture and the B picture in the first image signal to reduce distortion caused by encoding;
A third step of storing in a memory the second image signal of the I picture obtained in the first step and the second image signal of the P picture obtained in the second step,
In the first step,
A plurality of pixel data located around the target position in the second image signal of the I picture are selected from the first image signal of the I picture, and a class is generated from the level distribution of the selected pixel data 4 steps,
Corresponding to the student signal including coding distortion corresponding to the first image signal of the I picture and the second image signal of the I picture, which is obtained in advance for each class detected in the fourth step. A fifth step of generating coefficient data that minimizes an error from a teacher signal that does not include coding distortion;
A sixth step of selecting, from the first image signal of the I picture, a plurality of pixel data located around the position of interest in the second image signal of the I picture;
A seventh step of obtaining pixel data of a target position in the second image signal of the I picture by calculating the coefficient data generated in the fifth step and the plurality of pixel data selected in the sixth step And
In the second step,
From the first image signal of the P picture or B picture and the second image signal of the I picture or P picture stored in the memory, around the position of interest in the second image signal of the P picture or B picture An eighth step of selecting a plurality of pixel data located and generating a class from the level distribution of the selected pixel data;
A student signal that is obtained in advance for each class detected in the eighth step and includes coding distortion corresponding to the first image signal of the P picture or B picture and the second of the P picture or B picture. A ninth step of generating coefficient data that minimizes an error from a teacher signal corresponding to an image signal and not including coding distortion;
From the first image signal of the P picture or B picture and the second image signal of the I picture or P picture stored in the memory, around the position of interest in the second image signal of the P picture or B picture A tenth step of selecting a plurality of pixel data located;
The pixel data at the target position in the second image signal of the P picture or B picture is obtained by calculating the coefficient data generated in the ninth step and the plurality of pixel data selected in the tenth step. An image signal processing method comprising 11 steps . The first image signal of the I picture among the first image signals composed of a plurality of pixel data generated by decoding the digital image signal encoded in the MPEG system is converted and encoded. A first step of generating a second image signal of an I picture with reduced distortion associated with
A second step of generating a second image signal of the P picture and the B picture by performing transformation processing on the P picture and the B picture in the first image signal to reduce distortion caused by encoding;
A third step of storing in a memory the second image signal of the I picture obtained in the first step and the second image signal of the P picture obtained in the second step,
In the first step,
A plurality of pixel data located around the target position in the second image signal of the I picture are selected from the first image signal of the I picture, and a class is generated from the level distribution of the selected pixel data 4 steps,
Corresponding to the student signal including coding distortion corresponding to the first image signal of the I picture and the second image signal of the I picture, which is obtained in advance for each class detected in the fourth step. A fifth step of generating coefficient data that minimizes an error from a teacher signal that does not include coding distortion;
A sixth step of selecting, from the first image signal of the I picture, a plurality of pixel data located around the position of interest in the second image signal of the I picture;
A seventh step of obtaining pixel data of a target position in the second image signal of the I picture by calculating the coefficient data generated in the fifth step and the plurality of pixel data selected in the sixth step And
In the second step,
From the first image signal of the P picture or B picture and the second image signal of the I picture or P picture stored in the memory, around the position of interest in the second image signal of the P picture or B picture An eighth step of selecting a plurality of pixel data located and generating a class from the level distribution of the selected pixel data;
A student signal that is obtained in advance for each class detected in the eighth step and includes coding distortion corresponding to the first image signal of the P picture or B picture and the second of the P picture or B picture. A ninth step of generating coefficient data that minimizes an error from a teacher signal corresponding to an image signal and not including coding distortion;
From the first image signal of the P picture or B picture and the second image signal of the I picture or P picture stored in the memory, around the position of interest in the second image signal of the P picture or B picture A tenth step of selecting a plurality of pixel data located;
The coefficient data generated in the ninth step and the plurality of pixel data selected in the tenth step are calculated to obtain pixel data at the target position in the second image signal of the P picture or B picture. A program for causing a computer to execute an image signal processing method having 11 steps . The first image signal of the I picture among the first image signals composed of a plurality of pixel data generated by decoding the digital image signal encoded in the MPEG system is converted and encoded. The digital image signal obtained by encoding the teacher signal corresponding to the second image signal of the I picture in which distortion caused by the conversion is reduced is decoded, and the student signal corresponding to the first image signal of the I picture is decoded. A first decoding unit to obtain;
A first class detection unit that selects a plurality of pixel data located around a target position in the teacher signal of the I picture from the student signal of the I picture, and generates a class from the level distribution of the selected pixel data; ,
A first prediction tap selection unit that selects, from the student signal of the I picture, a plurality of pixel data located around the position of interest in the teacher signal of the I picture;
The I picture student for each class from the class detected by the first class detection unit, the plurality of pixel data selected by the first prediction tap selection unit, and the pixel data of the target position in the teacher signal A first calculation unit that obtains coefficient data that minimizes an error between a plurality of pixel data related to the signal and pixel data at a target position in the teacher signal of the I picture;
Conversion processing is performed on the first image signal of the P picture or B picture among the first image signals composed of a plurality of pixel data generated by decoding the digital image signal encoded in the MPEG system. The first picture of the P picture or B picture is decoded by decoding the digital picture signal obtained by coding the teacher signal corresponding to the second picture signal of the P picture or B picture that is reduced in distortion caused by the coding. A second decoding unit for obtaining a student signal corresponding to the image signal of
A memory for storing teacher signals of the I picture and the P picture;
A plurality of pixel data located around a target position in the teacher signal of the P picture or B picture is selected from the student signal of the P picture or B picture and the teacher signal of the I picture or P picture stored in the memory. A second class detection unit for generating a class from the level distribution of the selected pixel data;
A plurality of pixel data located around the position of interest in the teacher signal of the P picture or B picture is selected from the student signal of the P picture or B picture and the teacher signal of the I picture or P picture stored in the memory. A second prediction tap selection unit;
The P picture or B for each class from the class detected by the second class detection unit, the plurality of pixel data selected by the second prediction tap selection unit, and the pixel data of the target position in the teacher signal. a plurality of pixel data and the P-picture or the second and engaging number data generation Ru having an arithmetic unit for obtaining the coefficient data that minimizes the error between the target position of the pixel data in the teacher signal of the B picture according to the student signal of the picture apparatus. The first image signal of the I picture among the first image signals composed of a plurality of pixel data generated by decoding the digital image signal encoded in the MPEG system is converted and encoded. And decoding a digital image signal obtained by encoding a teacher signal corresponding to the second image signal of the I picture with reduced distortion caused by the conversion into a student signal corresponding to the first image signal of the I picture . A first step of obtaining
A second step of selecting a plurality of pixel data located around a target position in the teacher signal of the I picture from the student signal of the I picture and generating a class from the level distribution of the selected pixel data;
A third step of selecting a plurality of pixel data located around a target position in the teacher signal of the I picture from the student signal of the I picture;
From the class detected in the second step, the plurality of pixel data selected in the third step, and the pixel data of the target position in the teacher signal, a plurality of classes related to the student signal of the I picture for each class. A fourth step of obtaining coefficient data that minimizes an error between the pixel data and the pixel data at the target position in the teacher signal of the I picture;
Conversion processing is performed on the first image signal of the P picture or B picture among the first image signals composed of a plurality of pixel data generated by decoding the digital image signal encoded in the MPEG system. The first image of the P picture or B picture is decoded by decoding the digital image signal obtained by encoding the teacher signal corresponding to the second image signal of the P picture or B picture that has been reduced in distortion caused by encoding. A fifth step of obtaining a student signal corresponding to the image signal of
A sixth step of storing the I picture and P picture teacher signals in a memory;
A plurality of pixel data located around a target position in the teacher signal of the P picture or B picture is selected from the student signal of the P picture or B picture and the teacher signal of the I picture or P picture stored in the memory. A seventh step of generating a class from the level distribution of the selected pixel data;
A plurality of pixel data located around the position of interest in the teacher signal of the P picture or B picture is selected from the student signal of the P picture or B picture and the teacher signal of the I picture or P picture stored in the memory. An eighth step;
From the class detected in the seventh step, the plurality of pixel data selected in the eighth step, and the pixel data at the position of interest in the teacher signal, the student signal of the P picture or B picture for each class. a plurality of pixel data and the P-picture or B ninth step and engaging number data generation process of Ru with a seeking coefficient data that minimizes the error between the target position of the pixel data in the teacher signal of the picture according. The first image signal of the I picture among the first image signals composed of a plurality of pixel data generated by decoding the digital image signal encoded in the MPEG system is converted and encoded. And decoding a digital image signal obtained by encoding a teacher signal corresponding to the second image signal of the I picture with reduced distortion caused by the conversion into a student signal corresponding to the first image signal of the I picture . A first step of obtaining
A second step of selecting a plurality of pixel data located around a target position in the teacher signal of the I picture from the student signal of the I picture and generating a class from the level distribution of the selected pixel data;
A third step of selecting a plurality of pixel data located around a target position in the teacher signal of the I picture from the student signal of the I picture ;
From the class detected in the second step, the plurality of pixel data selected in the third step, and the pixel data of the target position in the teacher signal, a plurality of classes related to the student signal of the I picture for each class. A fourth step of obtaining coefficient data that minimizes an error between the pixel data and the pixel data at the target position in the teacher signal of the I picture;
Conversion processing is performed on the first image signal of the P picture or B picture among the first image signals composed of a plurality of pixel data generated by decoding the digital image signal encoded in the MPEG system. The first image of the P picture or B picture is decoded by decoding the digital image signal obtained by encoding the teacher signal corresponding to the second image signal of the P picture or B picture that has been reduced in distortion caused by encoding. A fifth step of obtaining a student signal corresponding to the image signal of
A sixth step of storing the I picture and P picture teacher signals in a memory;
A plurality of pixel data located around a target position in the teacher signal of the P picture or B picture is selected from the student signal of the P picture or B picture and the teacher signal of the I picture or P picture stored in the memory. A seventh step of generating a class from the level distribution of the selected pixel data;
A plurality of pixel data located around the position of interest in the teacher signal of the P picture or B picture is selected from the student signal of the P picture or B picture and the teacher signal of the I picture or P picture stored in the memory. An eighth step;
From the class detected in the seventh step, the plurality of pixel data selected in the eighth step, and the pixel data of the target position in the teacher signal, the student signal of the P picture or B picture for each class. executing a plurality of pixel data and the P-picture or the ninth step and the engaging speed data generating method Ru comprising the obtaining coefficient data that minimizes the error between the target position of the pixel data in the teacher signal of B picture in the computer according Program for.

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