static void
rgba_to_ycbcra709 (const Babl *conversion,
char *src,
char *dst,
long n)
{
while (n--)
{
double red = ((double *) src)[0];
double green = ((double *) src)[1];
double blue = ((double *) src)[2];
double alpha = ((double *) src)[3];
double luminance, cb, cr;
red = linear_to_gamma_2_2 (red);
green = linear_to_gamma_2_2 (green);
blue = linear_to_gamma_2_2 (blue);
luminance = 0.2126 * red + 0.7152 * green + 0.0722 * blue;
cb = (blue - luminance) / 1.8556;
cr = (red - luminance) / 1.5748;
((double *) dst)[0] = luminance;
((double *) dst)[1] = cb;
((double *) dst)[2] = cr;
((double *) dst)[3] = alpha;
src += sizeof (double) * 4;
dst += sizeof (double) * 4;
}
}
static void
rgba_to_hsv_step (char *src,
char *dst)
{
double hue, saturation, value;
double min, chroma;
double red = linear_to_gamma_2_2 (((double *) src)[0]);
double green = linear_to_gamma_2_2 (((double *) src)[1]);
double blue = linear_to_gamma_2_2 (((double *) src)[2]);
if (red > green)
{
value = MAX (red, blue);
min = MIN (green, blue);
}
else
{
value = MAX (green, blue);
min = MIN (red, blue);
}
chroma = value - min;
if (value < EPSILON)
saturation = 0.0;
else
saturation = chroma / value;
if (saturation < EPSILON)
{
hue = 0.0;
}
else
{
if (fabs (red - value) < EPSILON)
{
hue = (green - blue) / chroma;
if (hue < 0.0)
hue += 6.0;
}
else if (fabs (green - value) < EPSILON)
hue = 2.0 + (blue - red) / chroma;
else
hue = 4.0 + (red - green) / chroma;
hue /= 6.0;
}
((double *) dst)[0] = hue;
((double *) dst)[1] = saturation;
((double *) dst)[2] = value;
}
static void
table_init (void)
{
if (table_inited)
return;
table_inited = 1;
/* fill tables for conversion from integer to float */
{
int i;
for (i = 0; i < 1 << 8; i++)
{
float direct = i / 255.0;
table_8_F[i] = direct;
table_8g_F[i] = gamma_2_2_to_linear (direct);
}
}
/* fill tables for conversion from float to integer */
{
union
{
float f;
uint32_t s;
} u;
u.f = 0.0;
//u.s[0] = 0;
for (u.s = 0; u.s < 4294900000U; u.s += 32768)
{
int c;
int cg;
if (u.f <= 0.0)
{
c = 0;
cg = 0;
}
else
{
c = (u.f * 255.1619) + 0.5;
cg = (linear_to_gamma_2_2 (u.f) * 255.1619) + 0.5;
if (cg > 255) cg = 255;
if (c > 255) c = 255;
}
table_F_8[(u.s >> 15) & ((1 << 17)-1)] = c;
table_F_8g[(u.s >> 15) & ((1 << 17)-1)] = cg;
}
}
#if 0
/* fix tables to ensure 1:1 conversions back and forth */
if (0)
{
int i;
for (i = 0; i < 256; i++)
{
float f;
unsigned short *hi = ((unsigned short *) (void *) &f);
unsigned short *lo = ((unsigned short *) (void *) &f);
f = table_8_F[i];
*lo = 0;
table_F_8[*hi] = i;
f = table_8g_F[i];
*lo = 0;
table_F_8g[*hi] = i;
}
}
#endif
}
