Summary of Standardization Activities for Prepress Color Data Exchange Mitsuo KAJI* *Department of Image Information Engineering, Tokyo Institute of P

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1 Summary of Standardization Activities for Prepress Color Data Exchange Mitsuo KAJI* *Department of Image Information Engineering, Tokyo Institute of Polytechnics 1583, Iiyama, Atsugi-shi, Kanagawa, JAPAN Abstract The definition activities for color data exchange which have been performed in ISO/TC 130/WG2 are de scribed. This Working Group is charged with the responsibility of developing the color caliblation tools, color definitions, reference set of encoded data and data format definitions necessary to facilitate color data ex change within the graphic arts electronic prepress application area. Two standards have been completed. The first defines targets for input scanner calibration with transparency and reflection photographic products. The second standard provides a reference data set for CMYK to printed-color characterization. Works is still con tinuing on the development of a scanner caliblation target for use with negative films and on the development of default definitions for three-component color data exchange in CGATS/SC7 (Data Exchange) & SC8 (Color Data Definition). Joint activities with JWG2, 3 and 4 in JNC (Japan National Committee) for ISO/TC130 as well as activities with the CGATS (Committee for Graphic Arts Technologies Standards) and the industry SWOP" committee in USA are performing to provide default relationships between CMYK input data and me asured XYZ tristimulus values of results printed at or near the nominal aim. These data will provide a com mon reference for applications which provide CMYK output. Additional work is also underway to provide data for other common well defined printing conditions. A set of reference images (SCID: Standard Color Im age Data) are being developed by IPTS (Image Processing Technology Standards) SWG1 as the international standard in conjunction with JWG2 in JNC and ISO/TC130/WG2. These image data will be available in elec tronic form and will provide a common set of visual reference material for evaluation of data transfer, data compression, proofing and output devices. As for the media independent data format, the standardization works of TIFF/IT (Tag Image File Format for Image Technology) and JPEG Application Profile in which the compressed data format with JPEG algorithm is proposed have been continued in ISO/TC130/WG2. vities is explained in Chapter 4. Current status of these acti

4 Layout of patches, row and column numbering The hue angle, lightness, and chroma of the transmission target patches (1) -These values are specific to the product used to create the target and equal to maximum C* available at the hue angle and L* specified. They are to be defined by the manufacturer of the product used to make the target. The hue angle, lightness, and chroma of the reflection target patches (1) -These values are specific to the product used to create the target and equal to ma).zmunt C* available at the hue angle and L* specified They are to be defined by the manufacturer of the product used to make the target. Fig. 1 Lagout of color target for input scanner calibraction

5 Fig. Z Color gamut for a typical hue angle and chroma points of color patches

6 カラーデータ交換に係わる標準化の動向 ① ハードコピー出力システムにより複製される一つの色に対し,最適の網点%が求まるので,記録システム 191 値から, RGB CMY (K)の色空間間の変換特性を推定できる. で生ずる歪量に最適の色修整量を推定することができる. ② ハードコピー出力システムにおける色再現条件を, この色標本の再現特性を用いて指定できる. ③ 複写機印刷機器の製造業者や利用者にとって, ISO/TC130では,この出力ターゲットを実印刷したものを測色し,米国,ヨーロッパ,日纏めることになっており,そ装置の性能チェックを行う一般的なテストチャートとし国内委員会JWG2, て利用できる. 学会,画 ④ 入力ターゲットの色度値と複製された色の網点% JWG3, 像電子学会,写をメンバーとするれぞれの地区のため,国 JWG4の真学会,電 Reportに内では, TC130 エキスパート,印刷子写真学会の有識者標準画像印刷テスト及びTechnicaI Fig.3 第31巻第3号(1994) 本,そごとに色再現特性を評価した結果をTechnical SCID images 19

7 Fig. 4 Histogram comparision of N 2 (400LPI) and N 2 A (300LPI) images

9 exchange-application profile for compressed tag im age file interchange format" 11) D.Q.McDowell "Status of Graphic Arts Standards Activities" ISO/IEC JTC1/5C18/WG5 Meeting re port of colour experts, Steamboat Springs, June ) Andrew H. Mutz "Progress In Color Fax Stan 1) ISO/TC130/WG2 N347: ISO CD "Graphic technology-prepress digital data exchange-standard colour image data" 2) ISO CD "Graphic technology Spectral measurement and colorimetric computation for graphic arts images" 3) ISO CD "Graphic technology Prepress digital data exchange-colour targets for input scan ner calobration" 4) ISO CD "Graphic technology Prepress digital data exchange-input data for characterization of 4-color process printing targets" 5) IT8.9/1 Graphic technology-prepress Digital Data Exchange Publishing Interchange Language, Draft Revision 6 of IT8.9/1 6) IT8.9/2 Graphic technology-prepress digital data exchange-page/document Layout Specification, Draft of ANSI IT8.9 7) IT Graphic technology-prepress digital data exchange-tag image file format for image tech nology (TIFF/IT) 8) TIFF Revision 6.0 Final: Aldus Corporation, June ) ISO DIS "Digital Compression and Coding of Continuous tone Still Images Part 1 require ments and guideline" 10) ISO/ TC130/ WG2 N310 Proposal for Committee Draft: "Graphic technology Prepress digital data dards (ITU), An Unauthorized Biography" ISO/ IEC JTC1/SC18/WG5 Meeting report of colour ex perts, Steamboat Springs, June 1993

平成13年度事業報告

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