kc3-lang/libjpeg-turbo/src/cmyk.h

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• Hash : f74989d8
  Author :
  Date : 2025-09-25T11:32:45
  

  Clean up #include directives
  
  This is subtle, but #include <header.h> searches directories specified
  with -I, then system include directories.  #include "header.h" searches
  the current source directory, then directories specified with -I, then
  system include directories.
  
  Using bracketed #include directives for jpeglib.h, jinclude.h, jerror.h,
  cdjpeg.h, and turbojpeg.h only worked because the build system
  explicitly passed -I{source_directory}/src/ to the compiler.  Referring
  to 51cee0362998ec6f1eabac1e795f3b6e3ee639ea, it's better for the source
  code to have as few dependencies on our specific build system as
  possible.
  
  Since jpeglib.h, jinclude.h, jerror.h, and turbojpeg.h can be installed
  in system include directories, it's also better for internal references
  to those headers to resolve internally first, to avoid potential
  conflicts between the system-installed version of libjpeg-turbo and the
  version being built.  (Such conflicts would never have occurred with our
  build system, but they might have occurred due to misintegration with a
  downstream build system.)
  

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• src/cmyk.h

• /*
   * cmyk.h
   *
   * Copyright (C) 2017-2018, 2022, 2024-2025, D. R. Commander.
   * For conditions of distribution and use, see the accompanying README.ijg
   * file.
   *
   * This file contains convenience functions for performing quick & dirty
   * CMYK<->RGB conversion.  This algorithm is suitable for testing purposes
   * only.  Properly converting between CMYK and RGB requires a color management
   * system.
   */
  
  #ifndef CMYK_H
  #define CMYK_H
  
  #include "jinclude.h"
  #define JPEG_INTERNALS
  #include "jpeglib.h"
  #include "jsamplecomp.h"
  
  
  /* Fully reversible */
  
  INLINE
  LOCAL(void)
  rgb_to_cmyk(int maxval, _JSAMPLE r, _JSAMPLE g, _JSAMPLE b,
              _JSAMPLE *c, _JSAMPLE *m, _JSAMPLE *y, _JSAMPLE *k)
  {
    double ctmp = 1.0 - ((double)r / (double)maxval);
    double mtmp = 1.0 - ((double)g / (double)maxval);
    double ytmp = 1.0 - ((double)b / (double)maxval);
    double ktmp = MIN(MIN(ctmp, mtmp), ytmp);
  
    if (ktmp == 1.0) ctmp = mtmp = ytmp = 0.0;
    else {
      ctmp = (ctmp - ktmp) / (1.0 - ktmp);
      mtmp = (mtmp - ktmp) / (1.0 - ktmp);
      ytmp = (ytmp - ktmp) / (1.0 - ktmp);
    }
    *c = (_JSAMPLE)((double)maxval - ctmp * (double)maxval + 0.5);
    *m = (_JSAMPLE)((double)maxval - mtmp * (double)maxval + 0.5);
    *y = (_JSAMPLE)((double)maxval - ytmp * (double)maxval + 0.5);
    *k = (_JSAMPLE)((double)maxval - ktmp * (double)maxval + 0.5);
  }
  
  
  /* Fully reversible only for C/M/Y/K values generated with rgb_to_cmyk() */
  
  INLINE
  LOCAL(void)
  cmyk_to_rgb(int maxval, _JSAMPLE c, _JSAMPLE m, _JSAMPLE y, _JSAMPLE k,
              _JSAMPLE *r, _JSAMPLE *g, _JSAMPLE *b)
  {
    *r = (_JSAMPLE)((double)c * (double)k / (double)maxval + 0.5);
    *g = (_JSAMPLE)((double)m * (double)k / (double)maxval + 0.5);
    *b = (_JSAMPLE)((double)y * (double)k / (double)maxval + 0.5);
  }
  
  
  #endif /* CMYK_H */
  

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