JP2904277B2 - Noise reduction device - Google Patents
Noise reduction deviceInfo
- Publication number
- JP2904277B2 JP2904277B2 JP62280173A JP28017387A JP2904277B2 JP 2904277 B2 JP2904277 B2 JP 2904277B2 JP 62280173 A JP62280173 A JP 62280173A JP 28017387 A JP28017387 A JP 28017387A JP 2904277 B2 JP2904277 B2 JP 2904277B2
- Authority
- JP
- Japan
- Prior art keywords
- noise reduction
- video signal
- level
- circuit
- noise
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
Landscapes
- Television Signal Processing For Recording (AREA)
- Picture Signal Circuits (AREA)
Description
【発明の詳細な説明】
〔産業上の利用分野〕
本発明は、ノイズ低減装置に関し、より具体的には、
ビデオ信号のノイズを低減するノイズ低減装置に関す
る。
〔従来の技術〕
現在、ビデオ信号記録再生装置では、記録時又は再生
時のS/N改善のために、ビデオ信号の空間的・時間的相
関を利用したノイズ低減が行われている。第２図はフィ
ールド・メモリを利用した巡回型の代表的なノイズ低減
回路を示す。10は係数（１−Ｋ）を乗ずる乗算器、11は
加算器、12は係数Ｋを乗ずる乗算器、13は１フィールド
期間の遅延素子として機能するフィールド・メモリであ
る。但し、０≦Ｋ＜１である。このディジタル・フィル
タの伝達関数は、
Ｈ（Zf）＝（１−Ｋ）／（１−KZf -1）
であり、時間方向（即ち、フィールド間）での低域ろ波
特性を示す。ここで、Zf -1は１フィールド遅延に対応す
る単位遅延演算子である。この回路により、静止部分の
ノイズが低減される。
また、第２図の構成でメモリ13を1H（Ｈは水平走査期
間）のライン・メモリに置き換えることにより、垂直方
向での相関を利用したノイズ低減回路となる。
〔発明が解決しようとする問題点〕
しかし、時間的な相関を利用するノイズ低減回路で
は、被写体に動きがあるときには、残像が残るという問
題点があり、また、空間的な相関を利用するノイズ低減
回路では、エッジ部がなまるという問題点がある。
これに対しては、近年、ビデオ信号の動き部及びエッ
ジ部を検出して係数Ｋを適応的に切り換える方式も提案
されているが、簡易な動き検出、エッジ検出では、上記
問題点は解決されない。即ち、この適応制御方式では、
ノイズ低減による画質向上効果よりも、エッジのなまり
や残像が画質に及ぼす悪影響の方が大きいことが、しば
しば生じうる。
そこで本発明は、効果的なノイズ低減を行えるノイズ
低減装置を提示することを目的とする。
〔問題点を解決するたの手段〕
本発明に係るノイズ低減装置は、入力されたビデオ信
号のノイズを低減するノイズ低減手段と、前記ビデオ信
号の輝度レベルを検出するレベル検出手段と、前記ビデ
オ信号の動きを検出する動き検出手段と、前記レベル検
出手段及び動き検出手段の出力に基づいて前記ノイズ低
減手段を制御する制御手段とを備え、前記制御手段は、
前記ビデオ信号の輝度レベルが所定レベルよりも高い場
合に、前記ビデオ信号のノイズを低減する処理を行わな
いように前記ノイズ低減手段を制御し、前記ビデオ信号
の輝度レベルが前記所定レベル以下の場合に、前記動き
検出手段の出力に基づいて前記ビデオ信号のノイズを低
減するように前記ノイズ低減手段を制御することを特徴
とする。
〔作用〕
ビデオ信号が所定レベルよりも高い場合には、ノイズ
低減手段がノイズ低減処理を行なわないように制御する
ので、不必要にノイズ低減処理を行うことがなくなり、
それだけ、エッジのなまりや残像の発生を抑制できるこ
とになる。
〔実施例〕
以下、図面を参照して本発明の実施例を説明する。第
１図はビデオ・カメラに適用した実施例の構成ブロック
図を示す。
第１図において、20は光学像を電気信号に変換するCC
Dイメージ・センサ及びその駆動回路からなる撮像回路
である。22は、撮像回路20の出力の内、輝度（Ｙ）信号
のみを取り出し、その信号レベルにより利得を制御する
自動利得制御（AGC）回路、24は、γ補正回路、エッジ
補正回路などからなるＹ信号処理回路、26はＹ信号のレ
ベルを検出するレベル検出回路、28はA/D変換器であ
る。30は係数（１−Ｋ）の乗算器、32は加算器、34は係
数Ｋの乗算器、36はフィールド・メモリである。回路30
〜36は、第２図の回路10〜13と同じであり、ノイズ低減
のための巡回型回路を構成する。
38は、現信号と、フィールド・メモリ36による１フィ
ールド前の信号との比較により、動き部か静止部かを判
別する動き検出回路、40は、レベル検出回路26及び動き
検出回路38の検出結果に従い、乗算器30,34の係数Ｋを
制御する係数制御回路である。42はD/A変換器、44はベ
ースバンドの（Ｒ−Ｙ），（Ｂ−Ｙ）信号にエッジ補正
などを施した後、搬送色信号に変換する色（Ｃ）信号処
理回路、46は輝度信号と搬送色信号とを周波数多重する
混合回路、48はコンポジット・ビデオ信号の出力端子で
ある。
第１図の回路の動作を説明する。係数制御回路40は、
レベル検出回路26による検出レベルが所定値よりも高い
場合には、乗算器30,34の係数Ｋを０にして、ノイズ低
減動作が行われないようにし、検出レベルが所定値より
も低い場合には、動き検出回路38からの動き信号を参照
し、動き部と判定されるときには、係数Ｋを例えば０に
してノイズ低減動作が行われないようにし、静止部と判
定されるときには係数Ｋを例えば0.5にしてノイズ低減
動作を有効化する。即ち、一般に、ノイズは信号レベル
とは無関係に一定のレベルを保持すると考えられるの
で、信号レベルが所定値以下の場合にのみ、ノイズ低減
処理が有効になる。よって、この実施例では、信号レベ
ルに応じてノイズ低減処理をオン・オフする。
尚、上記実施例ではＹ信号に対してのみノイズ低減処
理をしているが、勿論、色ノイズを低減するためにＣ信
号に行ってもよい。また、ビデオ・テープ・レコーダの
再生系に使用してもよい。
〔発明の効果〕
以上の説明から容易に理解できるように、本発明によ
れば、ビデオ信号の輝度レベルが所定レベルよりも高い
場合にはノイズ低減処理を行わないので、不必要なノイ
ズ低減処理によって引き起こされる残像現象とエッジの
なまりの発生とを効果的に抑制することができる。これ
に加えて、本発明によれば、ビデオ信号の輝度レベルが
所定レベル以下の場合には信号レベルに応じた適応的な
ノイズ低減処理を行うので、ノイズ低減効果を低下させ
ることなく残像の発生やエッジのなまりを効果的に抑制
することもできる。The present invention relates to a noise reduction device, and more specifically, to a noise reduction device.
The present invention relates to a noise reduction device that reduces noise of a video signal. [Related Art] At present, in a video signal recording / reproducing apparatus, noise reduction using a spatial / temporal correlation of a video signal is performed in order to improve S / N during recording or reproduction. FIG. 2 shows a typical cyclic-type noise reduction circuit using a field memory. Reference numeral 10 denotes a multiplier for multiplying by a coefficient (1-K), 11 denotes an adder, 12 denotes a multiplier for multiplying by a coefficient K, and 13 denotes a field memory functioning as a delay element for one field period. However, 0 ≦ K <1. The transfer function of this digital filter is H (Z f ) = (1−K) / (1−KZ f −1 ), and shows a low-pass filtering characteristic in the time direction (that is, between fields). . Here, Z f -1 is a unit delay operator corresponding to one field delay. This circuit reduces noise in the stationary part. In addition, by replacing the memory 13 with a 1H (H is a horizontal scanning period) line memory in the configuration of FIG. 2, a noise reduction circuit utilizing correlation in the vertical direction is obtained. [Problems to be Solved by the Invention] However, the noise reduction circuit using the temporal correlation has a problem that an afterimage remains when the subject moves, and the noise using the spatial correlation In the reduction circuit, there is a problem that an edge portion is rounded. In response to this, in recent years, a method of detecting a moving portion and an edge portion of a video signal and adaptively switching the coefficient K has been proposed. However, the above-described problems cannot be solved by simple motion detection and edge detection. . That is, in this adaptive control method,
It can often happen that the image distortion is more adversely affected by the dullness of the edges and the afterimage than the effect of improving the image quality by noise reduction. Therefore, an object of the present invention is to provide a noise reduction device that can effectively reduce noise. [Means for Solving the Problems] A noise reduction device according to the present invention includes: a noise reduction unit configured to reduce noise of an input video signal; a level detection unit configured to detect a luminance level of the video signal; A motion detection unit that detects a motion of a signal; and a control unit that controls the noise reduction unit based on outputs of the level detection unit and the motion detection unit, wherein the control unit includes:
When the luminance level of the video signal is higher than a predetermined level, the noise reduction unit controls the noise reduction unit so as not to perform a process of reducing noise of the video signal, and when the luminance level of the video signal is lower than the predetermined level. Preferably, the noise reduction unit is controlled to reduce noise of the video signal based on an output of the motion detection unit. [Operation] When the video signal is higher than the predetermined level, the noise reduction unit controls so as not to perform the noise reduction process.
Accordingly, it is possible to suppress the occurrence of edge dullness and afterimage. Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing the configuration of an embodiment applied to a video camera. In FIG. 1, reference numeral 20 denotes a CC for converting an optical image into an electric signal.
This is an imaging circuit including a D image sensor and its driving circuit. Reference numeral 22 denotes an automatic gain control (AGC) circuit that extracts only a luminance (Y) signal from the output of the imaging circuit 20 and controls the gain according to the signal level. Reference numeral 24 denotes a Y correction circuit, an edge correction circuit, and the like. A signal processing circuit, 26 is a level detection circuit for detecting the level of the Y signal, and 28 is an A / D converter. Reference numeral 30 denotes a multiplier for the coefficient (1-K), 32 denotes an adder, 34 denotes a multiplier for the coefficient K, and 36 denotes a field memory. Circuit 30
36 are the same as the circuits 10 to 13 in FIG. 2, and constitute a cyclic circuit for noise reduction. Numeral 38 denotes a motion detecting circuit which determines whether a moving part or a stationary part by comparing the current signal with a signal one field before by the field memory 36, and 40 denotes a detection result of the level detecting circuit 26 and the motion detecting circuit 38. Is a coefficient control circuit for controlling the coefficient K of the multipliers 30, 34 according to 42 is a D / A converter, 44 is a color (C) signal processing circuit that converts the baseband (RY) and (BY) signals to edge color and the like and then converts them into carrier color signals. A mixing circuit 48 for frequency-multiplexing the luminance signal and the carrier chrominance signal, and 48 is an output terminal for a composite video signal. The operation of the circuit of FIG. 1 will be described. The coefficient control circuit 40
When the detection level by the level detection circuit 26 is higher than a predetermined value, the coefficient K of the multipliers 30 and 34 is set to 0 to prevent the noise reduction operation from being performed, and when the detection level is lower than the predetermined value, Refers to the motion signal from the motion detection circuit 38, sets the coefficient K to, for example, 0 to prevent the noise reduction operation from being performed when it is determined to be a moving part, and sets the coefficient K to, for example, when determined to be a stationary part. Set to 0.5 to enable noise reduction operation. That is, it is generally considered that noise keeps a constant level irrespective of the signal level. Therefore, the noise reduction processing is effective only when the signal level is equal to or lower than a predetermined value. Therefore, in this embodiment, the noise reduction processing is turned on / off according to the signal level. In the above embodiment, the noise reduction processing is performed only on the Y signal. However, the noise reduction processing may be performed on the C signal in order to reduce color noise. Further, it may be used for a reproduction system of a video tape recorder. [Effects of the Invention] As can be easily understood from the above description, according to the present invention, when the luminance level of the video signal is higher than the predetermined level, the noise reduction processing is not performed. It is possible to effectively suppress the afterimage phenomenon and the occurrence of rounding of the edge caused by the image. In addition, according to the present invention, when the luminance level of a video signal is equal to or lower than a predetermined level, adaptive noise reduction processing is performed in accordance with the signal level, so that generation of an afterimage can be performed without reducing the noise reduction effect. And rounding of edges can be effectively suppressed.
【図面の簡単な説明】
第１図はビデオ・カメラに適用した本発明の一実施例の
構成ブロック図、第２図は従来のノイズ低減回路の基本
構成ブロック図である。
20……撮像回路、２……輝度信号処理回路、26……レベ
ル検出回路、30,34……乗算器、36……フィールド・メ
モリ、38……動き検出回路、40……係数（Ｋ）制御回
路、44……色信号処理回路BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing a configuration of an embodiment of the present invention applied to a video camera, and FIG. 2 is a block diagram showing a basic configuration of a conventional noise reduction circuit. 20 imaging circuit, 2 luminance signal processing circuit, 26 level detection circuit, 30, 34 multiplier, 36 field memory, 38 motion detection circuit, 40 coefficient (K) Control circuit, 44 ... Color signal processing circuit
Claims (1)
減手段と、 前記ビデオ信号の輝度レベルを検出するレベル検出手段
と、 前記ビデオ信号の動きを検出する動き検出手段と、 前記レベル検出手段及び動き検出手段の出力に基づいて
前記ノイズ低減手段を制御する制御手段とを備え、 前記制御手段は、前記ビデオ信号の輝度レベルが所定レ
ベルよりも高い場合に、前記ビデオ信号のノイズを低減
する処理を行わないように前記ノイズ低減手段を制御
し、前記ビデオ信号の輝度レベルが前記所定レベル以下
の場合に、前記動き検出手段の出力に基づいて前記ビデ
オ信号のノイズを低減するように前記ノイズ低減手段を
制御することを特徴とするノイズ低減装置。(57) [Claims] Noise reduction means for reducing noise of an input video signal; level detection means for detecting a luminance level of the video signal; motion detection means for detecting motion of the video signal; level detection means and motion detection means A control unit that controls the noise reduction unit based on the output of the video signal. The control unit does not perform a process of reducing noise of the video signal when a luminance level of the video signal is higher than a predetermined level. And controlling the noise reducing means so as to reduce the noise of the video signal based on the output of the motion detecting means when the luminance level of the video signal is equal to or less than the predetermined level. A noise reduction device.
Priority Applications (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP62280173A JP2904277B2 (en) | 1987-11-05 | 1987-11-05 | Noise reduction device |
| US07/684,478 US5140424A (en) | 1987-07-07 | 1991-04-12 | Image signal processing apparatus with noise reduction |
| US07/904,558 US5323238A (en) | 1987-07-07 | 1992-06-26 | Image signal processing apparatus having improved storage control in accordance with an image signal level |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP62280173A JP2904277B2 (en) | 1987-11-05 | 1987-11-05 | Noise reduction device |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH01122273A JPH01122273A (en) | 1989-05-15 |
| JP2904277B2 true JP2904277B2 (en) | 1999-06-14 |
Family
ID=17621320
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP62280173A Expired - Lifetime JP2904277B2 (en) | 1987-07-07 | 1987-11-05 | Noise reduction device |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2904277B2 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2009145201A1 (en) * | 2008-05-27 | 2009-12-03 | 三洋電機株式会社 | Image processing device, image processing method, and imaging device |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH061691B2 (en) * | 1989-02-23 | 1994-01-05 | 新神戸電機株式会社 | Lead-acid battery manufacturing method |
| JPH03190478A (en) * | 1989-12-20 | 1991-08-20 | Mitsubishi Electric Corp | Video signal reproduction circuit |
| JP2536790B2 (en) * | 1990-07-12 | 1996-09-18 | 赤井電機株式会社 | Magnetic reproducing device with line noise canceller |
| JP4412042B2 (en) * | 2004-04-20 | 2010-02-10 | パナソニック株式会社 | Frame cyclic noise reduction method |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5853826B2 (en) * | 1978-06-01 | 1983-12-01 | 松下電器産業株式会社 | Image signal processing device |
-
1987
- 1987-11-05 JP JP62280173A patent/JP2904277B2/en not_active Expired - Lifetime
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2009145201A1 (en) * | 2008-05-27 | 2009-12-03 | 三洋電機株式会社 | Image processing device, image processing method, and imaging device |
Also Published As
| Publication number | Publication date |
|---|---|
| JPH01122273A (en) | 1989-05-15 |
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|---|---|---|---|
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