/*

 * cmyk.h

 *

 * Copyright (C) 2017-2018, 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></jinclude.h>

#define JPEG_INTERNALS

#include <jpeglib.h></jpeglib.h>

#include "jconfigint.h"

/* Fully reversible */

INLINE

LOCAL(void)

rgb_to_cmyk(JSAMPLE r, JSAMPLE g, JSAMPLE b, JSAMPLE *c, JSAMPLE *m,

            JSAMPLE *y, JSAMPLE *k)

{

  double ctmp = 1.0 - ((double)r / 255.0);

  double mtmp = 1.0 - ((double)g / 255.0);

  double ytmp = 1.0 - ((double)b / 255.0);

  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)(255.0 - ctmp * 255.0 + 0.5);

  *m = (JSAMPLE)(255.0 - mtmp * 255.0 + 0.5);

  *y = (JSAMPLE)(255.0 - ytmp * 255.0 + 0.5);

  *k = (JSAMPLE)(255.0 - ktmp * 255.0 + 0.5);

}

/* Fully reversible only for C/M/Y/K values generated with rgb_to_cmyk() */

INLINE

LOCAL(void)

cmyk_to_rgb(JSAMPLE c, JSAMPLE m, JSAMPLE y, JSAMPLE k, JSAMPLE *r, JSAMPLE *g,

            JSAMPLE *b)

{

  *r = (JSAMPLE)((double)c * (double)k / 255.0 + 0.5);

  *g = (JSAMPLE)((double)m * (double)k / 255.0 + 0.5);

  *b = (JSAMPLE)((double)y * (double)k / 255.0 + 0.5);

}

#endif /* CMYK_H */