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WO1992015169A1 - Procede et installation pour la production de signaux correspondant aux informations contenues dans des images a trame - Google Patents

Procede et installation pour la production de signaux correspondant aux informations contenues dans des images a trame Download PDF

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Publication number
WO1992015169A1
WO1992015169A1 PCT/DE1992/000085 DE9200085W WO9215169A1 WO 1992015169 A1 WO1992015169 A1 WO 1992015169A1 DE 9200085 W DE9200085 W DE 9200085W WO 9215169 A1 WO9215169 A1 WO 9215169A1
Authority
WO
WIPO (PCT)
Prior art keywords
video signals
digital
pixels
read
raster
Prior art date
Application number
PCT/DE1992/000085
Other languages
German (de)
English (en)
Inventor
Axel Bauer
Roland Czolbe
Herbert Dethardt
Original Assignee
Linotype-Hell Ag
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Linotype-Hell Ag filed Critical Linotype-Hell Ag
Publication of WO1992015169A1 publication Critical patent/WO1992015169A1/fr

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N1/00—Scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission; Details thereof
    • H04N1/40—Picture signal circuits
    • H04N1/40075—Descreening, i.e. converting a halftone signal into a corresponding continuous-tone signal; Rescreening, i.e. combined descreening and halftoning
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
    • G06T5/00—Image enhancement or restoration
    • G06T5/20—Image enhancement or restoration using local operators

Definitions

  • the invention is based on a method according to the type of the main claim.
  • the object of the present invention is to provide a method and an arrangement for generating signals which correspond to the information content of rastered images, the information content of the images being converted into electrical signals as uninfluenced as possible, without the occurrence of disturbing spectral components caused by the rasterization.
  • the method according to the invention with the features of the main claim has the advantage that electrical signals are available for the purpose of transmission and / or further processing, which largely correspond to the information content of the image, without spectral components caused by the screening leading to Moir Mo interference.
  • the arrangement according to the invention with the features of claim 12 has the advantage that the large amount of data resulting from the scanning can be processed with a relatively small amount of circuitry.
  • FIG. 1 shows a schematic illustration of a filter window used according to the method according to the invention
  • 3 shows a representation of the scanning of the original and the offset of the filter window
  • 4 shows a block diagram of an arrangement for carrying out the method according to the invention
  • FIG. 5 shows a more detailed block diagram of the arrangement according to FIG. 4,
  • FIG. 7 is a diagram for explaining an Kaiser-Bessel window, which is preferably used for low-pass filtering.
  • FIG. 1 schematically shows a filter window F in which 24 x 24 samples are taken into account.
  • the video signal represents one pixel in each case.
  • the pixels are hereinafter called fine pixels (FBP).
  • FBP fine pixels
  • the image to be transferred is used as a template and the grid in a corresponding manner as
  • Called template grid In the example shown in FIG. 1, the dimension b of a fine pixel is 1/8 of the raster width Rv of the original raster.
  • the halftone dots of the template are shown schematically by circles in FIG. 1.
  • the filter window F shown in FIG. 1 is applied to the entire template, shifted by an offset V in each case.
  • the offset V occurs row by row and column by column.
  • Rv is the grid size of the template grid or the image
  • Ra the raster width of the output raster or the size of the pixels, which are given by the filtered video signals
  • FIG. 2 shows an example of a template grid with grid points staggered line by line, so that diagonal grid lines are created, the grid width being Rv.
  • FIG. 3 shows schematically the displacement of the filter window F when scanning the template VL, which is interrupted in both directions in order to be able to display the filter window F on a favorable scale.
  • the filter windows F shown with different line types are slightly shifted in the figure for the sake of clarity, but this does not correspond to reality.
  • the total area scanned is larger than the template VL to be scanned in order to ensure perfect filtering of the template right up to the edge.
  • the filter window F is shifted n times in the scanning direction by the offset V (filter window F11, F12 ... F1n) until the entire original has been scanned in the scanning direction. Lines Z0 to Z23 are recorded. Then there is an offset V in the feed direction by eight lines, so that in the following Lines Z8 to Z31 are detected in the scanning direction (filter window F21, F22 ... F2n). This is repeated up to the filter window Fmn.
  • FIG. 4 shows a device for carrying out the method according to the invention as a block diagram.
  • the analog video signals generated by a scanning device 1 (not described in more detail) are fed to an analog / digital converter 2. Details that are important in the analog / digital conversion in the context of the method according to the invention will be explained in more detail later in connection with FIG. 6.
  • the analog / digital converter 2 generates a digital signal with n binary digits for each fine pixel, which are output in parallel to an image memory 3.
  • the image memory 3 essentially has the task of
  • the output signals of the filter processor 4 are fed to an interface 5, with which the gradation adjustment is possible.
  • the filtered digital video signals can be taken from the output 6.
  • FIG. 5 shows the arrangement according to FIG. 1 in more detail.
  • the analog / digital converter 2 supplies digital video signals with four binary digits.
  • each binary position of the digital video signals is processed separately.
  • the advantage that an adaptation of the arrangement to video signals with different bit widths, for example those with three binary digits, is possible in a simple manner without the individual circuits having to be changed.
  • the following description of the individual processing steps and the corresponding circuits therefore relates to a binary position of the digital video signals.
  • a series / parallel converter 7 the samples of 24 fine pixels, which are present in series at the output of the analog / digital converter 2, are converted into parallel signals. As a result, the number of samples that are required from a scan line for later filtering is forwarded in parallel.
  • a new 24-bit data word is then present at the output of the series / parallel converter 7 every 685 ns.
  • These data words are written into a read / write memory 8 which has 32 lines per binary position with 49152 fine pixels each - that is, a capacity of 24 x 64 K per binary position.
  • An address control unit 9, which contains an address counter for writing and reading, is assigned to the read / write memory 8.
  • the address control unit 9 takes over the control of the offset V of the filter window F in the feed direction. Furthermore, the end of the scanning process is determined by the address control unit 9 by counting the lines. Via a bus system 12, the address control unit 9 is given the offset V in the feed direction by a CPU (central processor unit) 13.
  • 24 rows are sequentially written into a memory of the column / row converter 10, so that an image section of 24 rows by 24 columns is created.
  • this image section is rotated by 90 °, so that 24 rows appear in parallel at the output of the column row converter 10.
  • the columns are read out sequentially, creating a 24-row sequential data stream from column 0 to column n.
  • a 24-line by 32-column image section is taken from the data stream into the window memory 11.
  • the offset V in the scanning direction is determined by appropriate control when reading out the data from the window memory 11.
  • Corresponding control signals are supplied by the CPU 13 via the bus system 12.
  • k represents the index of the respective binary position.
  • Pijk is a binary position of a fine pixel and can therefore only have the values 0 or 1.
  • the coefficients hij preferably correspond to an Kaiser-Bessel window multiplied by a Bessel function, which enables high blocking attenuation with a filter flank that is not too steep.
  • a Bessel function which enables high blocking attenuation with a filter flank that is not too steep.
  • FIG. 7 Examples of the coefficients for the fine pixels of a column or a row are shown in FIG. 7, which shows the course of the coefficients in one direction of the filter window F for an oversampling factor Ue. After the oversampling factor Ue has been entered, the CPU 13 determines suitable coefficients.
  • these "proposed" coefficients can be changed to adapt to the prevailing circumstances.
  • the multiplication of the sampled values of the fine pixels within the filter window F by the coefficients is carried out for a binary position with the aid of a read / write memory 14.
  • the coefficients are previously written into the read / write memory 14 by the CPU 13 via the bus system 12.
  • the sample values are fed from the filter memory 11 to the address inputs of the read / write memory 14.
  • the partial sums from the samples and the coefficients are available at data outputs of the read / write memory 14.
  • circuit 15 there follows an addition over one line in each case within filter window F and in circuit 16 an addition of the line totals over the columns of filter window F.
  • the filtered signal is thus available at the output of circuit 1.
  • the circuits 7 to 16 can be designed relatively simply by separating the individual binary positions. Short processing times are also possible thanks to parallel processing.
  • the binary digits are summarized in a computing unit 17 weighted according to their significance.
  • different quantizations and coefficients provide different word widths.
  • the present results are therefore shifted to the right until the most significant binary digit of the range of values resulting from the scanning of the original lies on the most significant binary digit of 12 binary digits.
  • the results are simultaneously cut to 12 binary digits.
  • the most significant binary position of the range of values resulting from the scanning of the original is current gradation setting determined and saved.
  • the control of the computing unit 17 also takes place via the bus system 12 from the CPU 13.
  • the computing unit 17 is followed by a circuit 18 for setting the gradation, which essentially consists of a read / write memory which is loaded via the bus system 12 with a look-up table (LUT).
  • the data stream comprising eight binary positions can then be extracted at output 6.
  • Using the LUT provides an excellent opportunity to adjust the entire arrangement.
  • a template is scanned with a given gray wedge of, for example, 27 steps and a desired amplitude value is entered into the LUT for each gray value.
  • any gradation it can also compensate for undesirable influences, such as tolerances in the scanning distance (gray fog suppression), different illuminance levels during scanning and changes in the overall amplitude when switching the filter characteristics.
  • FIG. 6 shows the relationship between the analog video signals Sa and the digital video signals Sd in the case of 3-bit quantization.
  • the values of the digital video signals are given in decimal, while the transmittance or the transparent portion of a fine pixel is plotted on the axis of the analog video signals Sa.
  • the analog / digital converter is adjusted with the offset adjustment in such a way that the quantization threshold between 0 and 1 is as high as possible, but at most in such a way that a 100% grid point is still certain can be distinguished from a 98% grid point and the 98% grid point is recognized with a digital value of> 0.
  • the above-mentioned disturbance variables, which lie below this quantization threshold, are therefore set to 0 (digital). This is achieved with an additional offset of half a quantization level compared to the linear adjustment. There is thus an additional suppression of disturbance variables in the black of 5%.
  • the analog / digital converter is adjusted with the gain adjustment so that the quantization threshold between 6 and 7 is as low as possible, but minimally so that a 0% grid point of a 2% - Screen point can be distinguished and the 2% screen point is recognized with a digital value ⁇ 7.
  • the above-mentioned disturbance variables which lie between the maximum signal Sa and the quantization threshold 7/6, are set to 7 (digital). This is achieved by a misalignment of the gain by one quantization level (1 LSB) compared to the linear adjustment in the light.
  • the interference rejection gain is 11.
  • the thresholds in light and in the depths cut off the disturbances mentioned above.
  • the digital signal Sd therefore practically only contains raster information.
  • the resulting non-linear transmission characteristic is compensated for by appropriate programming of the LUT 18.

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  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Signal Processing (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Theoretical Computer Science (AREA)
  • Image Processing (AREA)
  • Facsimile Image Signal Circuits (AREA)

Abstract

Dans un procédé et une installation pour la transmission d'images à trame, on dérive, par un balayage par ligne et par colonne, des signaux vidéo numériques pour des éléments d'image de dimensions sensiblement inférieures à la largeur de la trame. Les signaux vidéo sont soumis à un filtre passe-bas actif dans la direction des lignes et celle des colonnes avec une fenêtre de filtrage englobant au moins les éléments d'image correspondant à une maille de trame et décalée d'une position par ligne et par colonne.
PCT/DE1992/000085 1991-02-14 1992-02-08 Procede et installation pour la production de signaux correspondant aux informations contenues dans des images a trame WO1992015169A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE19914104467 DE4104467A1 (de) 1991-02-14 1991-02-14 Verfahren und anordnung zur erzeugung von signalen, welche dem informationsgehalt von gerasterten bildern entsprechen
DEP4104467.3 1991-02-14

Publications (1)

Publication Number Publication Date
WO1992015169A1 true WO1992015169A1 (fr) 1992-09-03

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PCT/DE1992/000085 WO1992015169A1 (fr) 1991-02-14 1992-02-08 Procede et installation pour la production de signaux correspondant aux informations contenues dans des images a trame

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CN (1) CN1065171A (fr)
DE (1) DE4104467A1 (fr)
WO (1) WO1992015169A1 (fr)

Families Citing this family (4)

* Cited by examiner, † Cited by third party
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DE4343362C2 (de) * 1993-04-08 1996-08-14 Linotype Hell Ag Werk Kiel Verfahren zur Erzeugung harmonischer Farbkorrekturen
US5559903A (en) * 1993-04-08 1996-09-24 Linotype Hell Ag Method for generating geometric masks with a digital color computer
CN1066880C (zh) * 1997-04-07 2001-06-06 鸿友科技股份有限公司 影像自动框取方法及其装置
CN101819378B (zh) * 2010-04-07 2011-11-16 陕西科技大学 一种测试印刷品加网线数和加网角度的方法

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US4381547A (en) * 1979-11-28 1983-04-26 Ricoh Co., Ltd. Picture deforming process
EP0153167A2 (fr) * 1984-02-17 1985-08-28 Minnesota Mining And Manufacturing Company Méthode d'amélioration d'image par balayage tramé
JPS61290866A (ja) * 1985-06-19 1986-12-20 Matsushita Graphic Commun Syst Inc カラ−画像処理装置
WO1990000780A1 (fr) * 1988-07-13 1990-01-25 Analogic Corporation Appareil de filtrage et de reechantillonnage simultanes de donnees numeriques
US4908780A (en) * 1988-10-14 1990-03-13 Sun Microsystems, Inc. Anti-aliasing raster operations utilizing sub-pixel crossing information to control pixel shading

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US4051536A (en) * 1975-03-14 1977-09-27 Xerox Corporation Electronic halftone imaging system
US3965290A (en) * 1975-03-21 1976-06-22 Dacom, Inc. Video-to-binary conversion apparatus having moire suppression characteristics
US4246614A (en) * 1979-12-26 1981-01-20 Xerox Corporation Binary graphic printer system having an electronic screen with shift control suited for rescreening
US4326258A (en) * 1980-01-31 1982-04-20 Ncr Canada Ltd - Ncr Canada Ltee Method and apparatus for reducing the gray scale resolution of a digitized image
DE3266409D1 (en) * 1982-10-09 1985-10-24 Hell Rudolf Dr Ing Gmbh Electrically controlled scanning apparatus and method for the moire-free scanning of raster copies
DE3309231A1 (de) * 1983-03-15 1984-09-20 Fogra Deutsche Forschungsgesellschaft für Druck- und Reproduktionstechnik e.V., 8000 München Verfahren zur offset/tiefdruck-konversion
GB2149994B (en) * 1983-11-14 1987-05-20 Matsushita Electric Ind Co Ltd Method and apparatus for processing video signals
JPS61203785A (ja) * 1985-03-07 1986-09-09 Dainippon Screen Mfg Co Ltd ２値画像デ−タの平滑化処理方法及びその装置
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EP0153167A2 (fr) * 1984-02-17 1985-08-28 Minnesota Mining And Manufacturing Company Méthode d'amélioration d'image par balayage tramé
JPS61290866A (ja) * 1985-06-19 1986-12-20 Matsushita Graphic Commun Syst Inc カラ−画像処理装置
WO1990000780A1 (fr) * 1988-07-13 1990-01-25 Analogic Corporation Appareil de filtrage et de reechantillonnage simultanes de donnees numeriques
US4908780A (en) * 1988-10-14 1990-03-13 Sun Microsystems, Inc. Anti-aliasing raster operations utilizing sub-pixel crossing information to control pixel shading

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CN1065171A (zh) 1992-10-07
DE4104467A1 (de) 1992-08-20

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