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21 December 1999 Black generation using lightness scaling
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This paper describes a method for constructing a lookup table relating a 3D CMY coordinate system to CMYK colorant amounts in a way that maximizes the utilization of the printer gamut volume. The method is based on an assumption, satisfied by most printers, that adding a black colorant to any combination of CMY colorants does not result in a color with more chroma. Therefore the CMYK gamut can be obtained from the CMY gamut by expanding it towards lower lightness values. Use of black colorant on the gray axis is enforced by modifying the initial distribution of CMY points through an approximate black generation transform. Lightness values of a resulting set of points in CIELAB space are scaled to fill the four-color gamut volume. The output CMYK values corresponding to the modified CIELAB colors are found by inverting a printer model. This last step determines a specific black use rate which can depend on the region of the color space.
© (1999) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Tomasz J. Cholewo "Black generation using lightness scaling", Proc. SPIE 3963, Color Imaging: Device-Independent Color, Color Hardcopy, and Graphic Arts V, (21 December 1999);


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