colorspace.c

void
dz_cmyk_to_rgb(fz_context *ctx, fz_colorspace *cs, const float *cmyk, float *rgb) {
  static cmsHTRANSFORM transform = NULL;

  if(!transform) {
    cmsHPROFILE cmyk_profile, rgb_profile;
    size_t cmyk_size, rgb_size;

    const char *cmyk_data = find_embedded_file("cmyk.icc", &cmyk_size);
    const char *rgb_data  = find_embedded_file("srgb.icc", &rgb_size);

    cmyk_profile = cmsOpenProfileFromMem(cmyk_data, cmyk_size);
    rgb_profile  = cmsOpenProfileFromMem(rgb_data, rgb_size);

    transform = cmsCreateTransform(cmyk_profile, TYPE_CMYK_FLT,
                                   rgb_profile,  TYPE_RGBA_FLT,
                                   INTENT_PERCEPTUAL, 0);

    cmsCloseProfile(cmyk_profile);
    cmsCloseProfile(rgb_profile);
  }

  float scaled_cmyk[4] = { cmyk[0] * 100.0, cmyk[1] * 100.0, cmyk[2] * 100.0, cmyk[3] * 100.0 };
  cmsDoTransform(transform, &scaled_cmyk, rgb, 1);
}