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

• Show log

  Commit

• Hash : 6ec8e41f
  Author :
  Date : 2024-06-13T11:52:13
  

  Handle lossless JPEG images w/2-15 bits per sample
  
  Closes #768
  Closes #769
  

Download

• src/cmyk.h

• /*
   * cmyk.h
   *
   * Copyright (C) 2017-2018, 2022, 2024, 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 */
  

Download