WO1993003574A1 - Procede et systeme d'impression pour produire des orientations de trame dans l'impression en couleurs numerique - Google Patents

Procede et systeme d'impression pour produire des orientations de trame dans l'impression en couleurs numerique Download PDF

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Publication number
WO1993003574A1
WO1993003574A1 PCT/DE1992/000592 DE9200592W WO9303574A1 WO 1993003574 A1 WO1993003574 A1 WO 1993003574A1 DE 9200592 W DE9200592 W DE 9200592W WO 9303574 A1 WO9303574 A1 WO 9303574A1
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WO
WIPO (PCT)
Prior art keywords
kmc
kmy
kmk
kmm
swc
Prior art date
Application number
PCT/DE1992/000592
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German (de)
English (en)
Inventor
Herbert Gibisch
Original Assignee
Siemens Nixdorf Informationssysteme 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 Siemens Nixdorf Informationssysteme Ag filed Critical Siemens Nixdorf Informationssysteme Ag
Publication of WO1993003574A1 publication Critical patent/WO1993003574A1/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
    • H04N1/405—Halftoning, i.e. converting the picture signal of a continuous-tone original into a corresponding signal showing only two levels
    • H04N1/4055—Halftoning, i.e. converting the picture signal of a continuous-tone original into a corresponding signal showing only two levels producing a clustered dots or a size modulated halftone pattern
    • H04N1/4058—Halftoning, i.e. converting the picture signal of a continuous-tone original into a corresponding signal showing only two levels producing a clustered dots or a size modulated halftone pattern with details for producing a halftone screen at an oblique angle
    • 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
    • H04N1/46—Colour picture communication systems
    • H04N1/52—Circuits or arrangements for halftone screening

Definitions

  • the invention relates to a method and a printing device for generating screen angles in digital color printing according to the preamble of claims 1 and 3, respectively.
  • Halftone processes are methods known in printing technology for controlling the output of shaded image areas via the size of the image pixels to be reproduced. Larger pixels produce darker areas, while small pixels result in lighter areas.
  • the resolution of an image is determined either by the number of pixels per inch or, if the pixels are combined in image lines, by the number of image lines per inch used. The latter is called the screen frequency and is measured in lines per inch (lpi).
  • the halftone process originally used in analog printing technology, is also used in a modified form in digital printing technology, e.g. B. applicable in printing devices such as ink, matrix and laser printers and in laser imagesetters, for the output of monochrome and colored image areas.
  • the conventional halftone process used in analogue printing technology is even more complex for the digital printing technique in the reproduction if shaded color areas and the finest differences in color nuance (different gray values) are to be printed.
  • the gray value of a color is the intensity of a color, e.g. For example, a red with a low gray value appears as pale pink, a red with a high gray value as a full, rich color.
  • each subtractive basic color cyan, magenta and yellow
  • subtractive basic color means that if white light (mixture of the additive basic colors red, green and blue (RGB colors)) is reflected on the subtractive basic color, then each of these subtractive basic colors absorbs at least one color of the additive Primary colors.
  • the whole picture is created by printing the subtractive basic colors and additionally the color black successively (according to the overlay principle).
  • the subtractive basic colors (cyan, gastric ta, yellow) and the color black are referred to below as basic colors (C, M, Y, K. for cyan, magenta, yellow and black).
  • the printing of the color black is necessary because, due to color impurities in the subtractive primary colors, the additive mixture of these three subtractive primary colors does not produce a pure black tone.
  • a so-called screen angle is used for each of the primary colors C, M, Y, K.
  • the screen angle is the angle at which the image lines of the basic color C, M, Y, K are rotated with respect to the horizontal.
  • Screen angles used for the individual primary colors C, M, Y, K are, for example, screen angles of 0 ° or 90 °, 15 °, 45 ", 75" in the order mentioned for the colors yellow, magenta, black and cyan.
  • the screen angle of 90 ° for the color yellow means only a rotation of the screen by 90 ° with respect to the 0 ° screen, without changing anything for the print image to be created.
  • the basic colors C, M, Y, K used in analog printing technology are not really transparent for cost reasons, so that the image pixels of the individual basic colors C, M, Y, K have to be offset from one another in order to Avoid false colors due to extensive color overlaps.
  • a 6x6 halftone cell with 36 cell elements is required in a 300 dpi printer.
  • the degree of filling of this halftone cell indicates how many cell elements (dots) are set. If, for example, nine cell elements are set in the 6x6 halftone cell, this corresponds to a degree of filling of 25%. If these halftone cells are strung together in rows and columns over larger areas, they appear as rows, the raster angle indicating the angle of these rows to the horizontal or vertical.
  • the matrix or halftone cells are designed. For example, If a color separation is to be carried out, care must be taken that the screen angle and the screen filling of the matrix or halftone cell are optimized such that, if possible, no moiré patterns are produced. If you still want to print out a color, e.g. B. create with a thermal transfer printer, the matrix or halftone cell must also be designed so that the cleanest possible and rich colors. For this, it is advantageous if the number of matrix or cell elements is as small as possible, since this increases the image resolution.
  • WO 90/05423 is a device and a Process known with which or with which shaded color areas and the finest differences in color shade are printed according to the halftone method.
  • a screen angle is introduced for each color printout.
  • dither matrices produced according to the dither method are rotated with respect to their coordinates by a 3x3 transformation matrix.
  • this z B. with a requirement to print 20 pages (A4) per minute with a maximum of 80 color expressions for a four-color printer, even with the fastest microprocessors currently available cannot be handled in time.
  • FIG. 1 shows a flow diagram for digital color printing in block diagram representation
  • FIG. 2 shows a microcomputer system of a printing device for carrying out the flow chart shown in FIG. 1,
  • 3a to 3d a set of 4x4 conversion matrices for the basic color cyan, each with a degree of filling of 25%,
  • 4a to 4d a set of 4x4 conversion matrices for the basic color magenta, each with a degree of filling of 50%,
  • Figure 5 is a cross-line, a screen angle of 75 *-generating arrangement of the Konversionsmatrizen for the color cyan in accordance with Figures 3a to 3d,
  • FIG. 6 shows a cross-column arrangement of the conversion matrices for the basic color magenta according to FIGS. 4a to 4d, producing a screen angle of 15 °
  • FIG. 7 shows a 4x4 conversion matrix for the basic color yellow with a degree of filling of 50%
  • FIG. 8 shows a 4x4 conversion matrix for the basic color black with a degree of filling of 25%
  • FIG. 9 shows an arrangement of the conversion matrix for the basic color yellow according to FIG. 7 spanning rows or columns and producing a screen angle of 90 ′′
  • FIG. 10 shows an arrangement of the conversion matrix for the basic color black according to FIG. 8 that spans rows or columns and generates a raster angle of 45 * .
  • Figure 1 shows a block diagram of a flow chart for digital color printouts, z. B. in ink, thermal transfer and laser printers.
  • the sequence diagram can also be used in the combination of laser imagesetter and analog printing technology.
  • the sequence shown begins with the fact that color pixels of a template V contain the basic colors Y, M, C, K (yellow, magenta, cyan and black) in digitally coded color intensities IY, IM, IC, IK of the color pixels
  • Signal values SWY, SWM, SWC, SWK can be separated. This process, known as color separation, is known to the person skilled in the art.
  • B known from the publication "Digital Halftoning for Monochrome and Color Printing" and WO 90/05423.
  • Dither matrices are preferably used as conversion matrices KMY, KMM, KMC, KMK, but these can also be replaced by any other conversion matrices.
  • the dither matrices and the dither method are known to the person skilled in the art from the publication "Digital Halftoning for Monochrome and Color Printing" and WO 90/05423. A detailed description in the context of this exemplary embodiment is therefore omitted.
  • the set k of conversion matrices KMY, KMM, KMC, KMK is freely selectable in terms of the number k of its conversion matrices. So z.
  • each individual conversion matrix KMY, KMM, KMC, KMK does not differ from the others with regard to the color intensity IY, IM, IC, IK to be reproduced.
  • GFY, GFM, GFC, GFK is generated in rows or columns, for the selection of the conversion matrix KMY, KMM, KMC, KMK from the set k of conversion matrices either the calculation formula (1) or the calculation formula (2 ) be used.
  • FIG. 2 shows a microcomputer system 1 of a printing device 2, which is connected to a mainframe 3 (HOST) (double arrow in FIG. 2).
  • the printing device 2 is designed, for example, as a single-pass printer.
  • a recording medium to be printed for the individual color printouts is guided past several color print heads in succession.
  • This also increases the risk that register errors will occur. These register errors are then the cause of the moiré pattern mentioned at the beginning.
  • the color-separated signal values SWY, SWM, SWC, SWK of the template V according to FIG. 1 are transferred from the mainframe computer 3 to the microcomputer system 1 sequentially for conversion.
  • the various sets are k of convergence sionsmatrizen KMY, KMM, KMC, KMK for the 'basic colors Y, M, C, K with the different color intensities IY, IM, IC, IK stored.
  • the microprocessor 13 accesses the data in the converter for converting the separated signal values SWY, SWM, SWC, SWK Working memory 13 stored sets k of conversion matrices KMY, KMM, KMC, KMK. Access is based on the formula (1) and (2).
  • the modulo calculation carried out in this calculation form can be carried out in a simple manner without great computation effort, since the calculation steps necessary for this calculation can be carried out without additional programming with the microprocessor 12.
  • either the row or the column of the graphic formats GFY, GFM, GFC, GFK buffered in the mass memory 14 must be used for the converted signal values SWY, SWM, SWC , SWK be known. This can also be achieved by means of a memory management for the mass storage 14 carried out by the microprocessor 12. If all of the signal values SWY, SWM, SWC, SWK converted in the graphic format GFY, GFM, GFC, GFK are temporarily stored in the mass memory 14 by the dither method, the stored values can be accessed by the microprocessor 12 in the mass memory 14 by means of specifically controlled accesses Via the FIFO modules 15 ...
  • Each of these four conversion matrices KMC has four set matrix elements ME (black rectangles in FIGS. 3a to 3d).
  • the number of matrix elements ME set corresponds exactly to the degree of filling of the respective conversion matrix KMC. With four set matrix elements ME of 16 possible, this corresponds to a degree of filling of 25%. This degree of filling corresponds exactly to the color intensity IC of the separated signal value SWC according to FIG. 1.
  • the four set matrix elements ME of the four conversion matrices KMC are not selected arbitrarily, but rather in a targeted manner for generating a raster angle for the basic color cyan C.
  • the four conversion matrices KMC thus result in the figures 3a to 3d Arrangement shown in which the set matrix elements ME of the conversion matrices KMC are arranged in columns, each in different micro-columns MSP, for the creation of the graphic format GFC with 12 lines (lines 0 to 11) and 12 columns (columns 0 to 11) ) according to FIG. 5, the conversion matrices KMC according to FIGS.
  • all conversion matrices KMM also have one Filling level of 50%.
  • This in turn means that half of the 16 matrix elements ME are set by each conversion matrix KMM.
  • the setting of the individual matrix elements ME is again not arbitrary, but is based on a screen angle of 15 * to the horizontal that is optimally highlighted for the basic color Magenta M in analog printing technology. When this raster angle and the degree of filling are taken into account, z.
  • the set matrix elements ME of the conversion matrices KMM are arranged line by line, in each case in different micro-lines MZE.
  • the conversion matrices KMM in FIGS. 4a to 4d are arranged column by column by the required screen angle of 15 * for the matrix elements ME arranged line by line in the micro-lines MZE different in pairs.
  • FIG. 5 shows the graphic format GFC created from the four conversion matrices KMC in accordance with FIGS. 3a to 3d, as it is temporarily stored in the mass memory 14 according to FIG. 2 for the color expression of the basic color cyan C.
  • the graphic format GFC is structured line by line, i. H.
  • the individual conversion matrices KMC according to FIGS. 3a to 3d are arranged line by line with the aid of the calculation formula (1).
  • the areal arrangement of the conversion matrices KMC shown in FIG. 5 shown in FIGS. 3a to 3d results from this.
  • FIG. 5 shows that the grid angle of 75 ° automatically results for the conversion matrices KMC arranged in the manner described.
  • FIG. 6 shows the graphic format GFM created from the four conversion matrices KMC according to FIGS. 4a to 4d, as it is temporarily stored in the mass memory 14 according to FIG. 2 for the color printout of the primary color magenta M.
  • the graphic format GFM is structured in columns, ie the individual conversion matrices KMC according to FIGS. 4a to 4d are arranged in columns using the calculation formula (2). In the inter-column interplay, this results in the areal arrangement of the conversion matrices KMM shown in FIG. 6 according to FIGS. 4a to 4d.
  • FIG. 6 shows that for the conversion matrics KMM arranged in the described manner, the screen angle of 15 * automatically results.
  • FIG. 1 also shows the conversion matrix KMY degree of efficiency of 50%. This in turn is equivalent to the fact that half of the 16 matrix elements ME of the conversion matrix KMY are set.
  • the setting of the individual matrix elements ME is again not arbitrary, but is based on an angle of 90 ° to the horizontal that is optimally emphasized in the analog printing technology for the basic color yellow Y. Likewise, the screen angle could also have been 0 °, without this having changed anything in the printed image. If the grid angle of 90 ° and the degree of filling are taken into account, B. the arrangement set in FIG. 7, in which the set matrix elements ME of the conversion matrix KMY are arranged in two microgaps MSP.
  • the conversion matrix KMK also has a degree of filling of 25%. on. This in turn means that half of the 16 matrix elements ME of the conversion matrix KMK are set.
  • the setting of the individual matrix elements ME is again not arbitrary, but is based on an angle of 45 ° to the horizontal that is optimally emphasized in the analog printing technology for the basic color black K. If the grid angle of 45 ° and the degree of filling are taken into account, B. the arrangement shown in FIG. 8, in which the set matrix elements ME of the conversion matrix KMK are arranged diagonally.
  • FIG. 9 shows the graphic format GFY created from the conversion matrix KMY according to FIG. 7, as it is temporarily stored in the mass memory 14 according to FIG. 2 for the color expression of the basic color yellow.
  • the GFY graphics format is structured in columns or rows, i.e. H.
  • the conversion matrix KMY according to FIG. 7 is arranged in rows or columns using the calculation formula (1) or (2).
  • the areal arrangement of the conversion matrix KMY shown in FIG. 9 shown in FIG. 9 results from this.
  • FIG. 9 shows that for the conversion matrix KMY arranged in the manner described, the screen angle of 90 automatically results ° results.
  • FIG. 10 shows the graphic format GFK created from the conversion matrix KMK according to FIG. 8, as it is temporarily stored in the mass memory 14 according to FIG. 2 for the color expression of the basic color black.
  • the GRP graphics format is in turn structured in columns or rows, i.e. H. the conversion matrix KMK according to FIG. 8 is arranged row-wise or column-wise with the aid of the calculation formula (1) or (2).
  • FIG. 10 shows that for the conversion matrix KMK arranged in the manner described, the screen angle of 45 ° results automatically.

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  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Signal Processing (AREA)
  • Facsimile Image Signal Circuits (AREA)

Abstract

Ce procédé et ce système permettent de convertir des valeurs de signaux (SWY, SWM, SWC, SWK) codées de manière numérique et séparées en fonction des intensités de couleurs (IY, IM, IC, IK) des pixels colorés d'un modèle original (V), au moyen de jeux (k) de matrices de conversion (KMY, KMM, KMC, KMK). Pour finir, les valeurs de signaux (SWY, SWM, SWC, SWK) converties sont disposées à l'aide d'un calcul modulo, en lignes ou en colonnes, en vue d'une impression couleur (Y, M, C, K) dans un format graphique (GFY, GFM, GFC, GFK) de sorte que, dans la combinaison par recouvrement des lignes ou des colonnes des valeurs de signaux converties (SWY, SWM, SWC, SWK), une orientation de trame se fasse pour l'impression couleur (Y, M, C, K) concernée.
PCT/DE1992/000592 1991-07-26 1992-07-21 Procede et systeme d'impression pour produire des orientations de trame dans l'impression en couleurs numerique WO1993003574A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DEP4124876.7 1991-07-26
DE4124876 1991-07-26

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WO1993003574A1 true WO1993003574A1 (fr) 1993-02-18

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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE4313448A1 (de) * 1992-05-22 1993-11-25 Kienlin Albrecht Von Verfahren zur elektronischen Verarbeitung ein- oder mehrfarbiger Halbton-Bildvorlagen
US5548407A (en) * 1992-05-22 1996-08-20 Albrecht von Kienlin Process for electronic processing of multi-colored continuous-tone images
EP1079603A2 (fr) * 1999-08-23 2001-02-28 Seiko Epson Corporation Procédé et appareil pour obtenir des images en couleur demi-teintes
CN106979759A (zh) * 2017-04-16 2017-07-25 合肥芯碁微电子装备有限公司 一种网版制版丝网角度的测量装置及其测量方法

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4084183A (en) * 1970-03-18 1978-04-11 Dr. Ing. Rudolf Hell Gmbh. Method for the electro-optical reproduction of half-tone pictures
US4507685A (en) * 1982-06-25 1985-03-26 Canon Kabushiki Kaisha Image recording device
US4884080A (en) * 1985-01-31 1989-11-28 Kabushiki Kaisha Toshiba Color image printing apparatus

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4084183A (en) * 1970-03-18 1978-04-11 Dr. Ing. Rudolf Hell Gmbh. Method for the electro-optical reproduction of half-tone pictures
US4507685A (en) * 1982-06-25 1985-03-26 Canon Kabushiki Kaisha Image recording device
US4884080A (en) * 1985-01-31 1989-11-28 Kabushiki Kaisha Toshiba Color image printing apparatus

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE4313448A1 (de) * 1992-05-22 1993-11-25 Kienlin Albrecht Von Verfahren zur elektronischen Verarbeitung ein- oder mehrfarbiger Halbton-Bildvorlagen
US5548407A (en) * 1992-05-22 1996-08-20 Albrecht von Kienlin Process for electronic processing of multi-colored continuous-tone images
EP1079603A2 (fr) * 1999-08-23 2001-02-28 Seiko Epson Corporation Procédé et appareil pour obtenir des images en couleur demi-teintes
EP1079603A3 (fr) * 1999-08-23 2002-08-07 Seiko Epson Corporation Procédé et appareil pour obtenir des images en couleur demi-teintes
US6864996B1 (en) 1999-08-23 2005-03-08 Seiko Epson Corporation Image processor and image processing method, and printer system equipped with image processor
CN106979759A (zh) * 2017-04-16 2017-07-25 合肥芯碁微电子装备有限公司 一种网版制版丝网角度的测量装置及其测量方法

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