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-rw-r--r--src/convert.c154
1 files changed, 108 insertions, 46 deletions
diff --git a/src/convert.c b/src/convert.c
index 9a2c3d9..a998d66 100644
--- a/src/convert.c
+++ b/src/convert.c
@@ -53,6 +53,106 @@ static void ciexyz_to_rgb(const libcolour_ciexyz_t* restrict from, libcolour_rgb
to->B = to->Minv[2][0] * X + to->Minv[2][1] * Y + to->Minv[2][2] * Z;
}
+#define REGULAR(s, t) ((t) <= (s)->transition ? (s)->slope * (t) : (1 + (s)->offset) * pow((t), 1 / (s)->gamma) - (s)->offset)
+#define INVREGULAR(s, t) ((t) <= (s)->transitioninv ? (t) / (s)->slope : pow(((t) + (s)->offset) / (1 + (s)->offset), (s)->gamma))
+
+static void rgb_encode(libcolour_rgb_t* restrict colour, const libcolour_rgb_t* restrict space)
+{
+ double r_sign = 1, g_sign = 1, b_sign = 1;
+ switch (space->encoding_type) {
+ case LIBCOLOUR_ENCODING_TYPE_LINEAR:
+ break;
+ case LIBCOLOUR_ENCODING_TYPE_SIMPLE:
+ case LIBCOLOUR_ENCODING_TYPE_REGULAR:
+ if (colour->R < 0) r_sign = -1, colour->R = -colour->R;
+ if (colour->G < 0) g_sign = -1, colour->G = -colour->G;
+ if (colour->B < 0) b_sign = -1, colour->B = -colour->B;
+ if (space->encoding_type == LIBCOLOUR_ENCODING_TYPE_SIMPLE) {
+ colour->R = pow(colour->R, 1 / space->gamma);
+ colour->G = pow(colour->G, 1 / space->gamma);
+ colour->B = pow(colour->B, 1 / space->gamma);
+ } else {
+ colour->R = REGULAR(space, colour->R);
+ colour->G = REGULAR(space, colour->G);
+ colour->B = REGULAR(space, colour->B);
+ }
+ colour->R *= r_sign;
+ colour->G *= g_sign;
+ colour->B *= b_sign;
+ break;
+ case LIBCOLOUR_ENCODING_TYPE_CUSTOM:
+ colour->R = (space->to_encoded_red)(colour->R);
+ colour->G = (space->to_encoded_green)(colour->G);
+ colour->B = (space->to_encoded_blue)(colour->B);
+ break;
+ default:
+ fprintf(stderr, "libcolour: invalid encoding type\n");
+ abort();
+ }
+}
+
+static void rgb_decode(libcolour_rgb_t* restrict colour, const libcolour_rgb_t* restrict space)
+{
+ double r_sign = 1, g_sign = 1, b_sign = 1;
+ switch (space->encoding_type) {
+ case LIBCOLOUR_ENCODING_TYPE_LINEAR:
+ break;
+ case LIBCOLOUR_ENCODING_TYPE_SIMPLE:
+ case LIBCOLOUR_ENCODING_TYPE_REGULAR:
+ if (colour->R < 0) r_sign = -1, colour->R = -colour->R;
+ if (colour->G < 0) g_sign = -1, colour->G = -colour->G;
+ if (colour->B < 0) b_sign = -1, colour->B = -colour->B;
+ if (space->encoding_type == LIBCOLOUR_ENCODING_TYPE_SIMPLE) {
+ colour->R = pow(colour->R, space->gamma);
+ colour->G = pow(colour->G, space->gamma);
+ colour->B = pow(colour->B, space->gamma);
+ } else {
+ colour->R = INVREGULAR(space, colour->R);
+ colour->G = INVREGULAR(space, colour->G);
+ colour->B = INVREGULAR(space, colour->B);
+ }
+ colour->R *= r_sign;
+ colour->G *= g_sign;
+ colour->B *= b_sign;
+ break;
+ case LIBCOLOUR_ENCODING_TYPE_CUSTOM:
+ colour->R = (space->to_decoded_red)(colour->R);
+ colour->G = (space->to_decoded_green)(colour->G);
+ colour->B = (space->to_decoded_blue)(colour->B);
+ break;
+ default:
+ fprintf(stderr, "libcolour: invalid encoding type\n");
+ abort();
+ }
+}
+
+#undef REGULAR
+#undef INVREGULAR
+
+static int rgb_same_gamma(const libcolour_rgb_t* restrict a, const libcolour_rgb_t* restrict b)
+{
+ if (a->encoding_type != b->encoding_type)
+ return 0;
+ switch (a->encoding_type) {
+ case LIBCOLOUR_ENCODING_TYPE_SIMPLE:
+ return a->gamma == b->gamma;
+ case LIBCOLOUR_ENCODING_TYPE_REGULAR:
+ return a->gamma == b->gamma &&
+ a->offset == b->offset &&
+ a->slope == b->slope &&
+ a->transition == b->transition;
+ case LIBCOLOUR_ENCODING_TYPE_CUSTOM:
+ return a->to_encoded_red == b->to_encoded_red &&
+ a->to_encoded_green == b->to_encoded_green &&
+ a->to_encoded_blue == b->to_encoded_blue &&
+ a->to_decoded_red == b->to_decoded_red &&
+ a->to_decoded_green == b->to_decoded_green &&
+ a->to_decoded_blue == b->to_decoded_blue;
+ default:
+ return 1;
+ }
+}
+
static void to_rgb(const libcolour_colour_t* restrict from, libcolour_rgb_t* restrict to)
{
int have_gamma = 0, with_gamma = to->with_gamma;
@@ -64,7 +164,11 @@ static void to_rgb(const libcolour_colour_t* restrict from, libcolour_rgb_t* res
case LIBCOLOUR_RGB:
if (!memcmp(from->rgb.M, to->M, sizeof(double[3][3]))) {
have_gamma = from->rgb.with_gamma;
- *to = from->rgb;
+ to->R = from->rgb.R;
+ to->G = from->rgb.G;
+ to->B = from->rgb.B;
+ if (have_gamma && with_gamma && !rgb_same_gamma(&from->rgb, to))
+ rgb_decode(to, &from->rgb), have_gamma = 0;
break;
}
/* fall through */
@@ -77,51 +181,9 @@ static void to_rgb(const libcolour_colour_t* restrict from, libcolour_rgb_t* res
if (have_gamma != with_gamma) {
if (with_gamma) {
- switch (to->encoding_type) {
- case LIBCOLOUR_ENCODING_TYPE_LINEAR:
- break;
- case LIBCOLOUR_ENCODING_TYPE_SIMPLE:
- to->R = pow(to->R, 1 / to->gamma);
- to->G = pow(to->G, 1 / to->gamma);
- to->B = pow(to->B, 1 / to->gamma);
- break;
- case LIBCOLOUR_ENCODING_TYPE_REGULAR:
- to->R = to->R <= to->transition ? to->slope * to->R : (1 + to->offset) * pow(to->R, 1 / to->gamma) - to->offset;
- to->G = to->G <= to->transition ? to->slope * to->G : (1 + to->offset) * pow(to->G, 1 / to->gamma) - to->offset;
- to->B = to->B <= to->transition ? to->slope * to->B : (1 + to->offset) * pow(to->B, 1 / to->gamma) - to->offset;
- break;
- case LIBCOLOUR_ENCODING_TYPE_CUSTOM:
- to->R = (to->to_encoded_red)(to->R);
- to->G = (to->to_encoded_green)(to->G);
- to->B = (to->to_encoded_blue)(to->B);
- break;
- default:
- fprintf(stderr, "libcolour: invalid encoding type\n");
- abort();
- }
+ rgb_encode(to, to);
} else {
- switch (to->encoding_type) {
- case LIBCOLOUR_ENCODING_TYPE_LINEAR:
- break;
- case LIBCOLOUR_ENCODING_TYPE_SIMPLE:
- to->R = pow(to->R, to->gamma);
- to->G = pow(to->G, to->gamma);
- to->B = pow(to->B, to->gamma);
- break;
- case LIBCOLOUR_ENCODING_TYPE_REGULAR:
- to->R = to->R <= to->transitioninv ? to->R * to->slope : pow((to->R + to->offset) / (1 + to->offset), to->gamma);
- to->G = to->G <= to->transitioninv ? to->G * to->slope : pow((to->G + to->offset) / (1 + to->offset), to->gamma);
- to->B = to->B <= to->transitioninv ? to->B * to->slope : pow((to->B + to->offset) / (1 + to->offset), to->gamma);
- break;
- case LIBCOLOUR_ENCODING_TYPE_CUSTOM:
- to->R = (to->to_decoded_red)(to->R);
- to->G = (to->to_decoded_green)(to->G);
- to->B = (to->to_decoded_blue)(to->B);
- break;
- default:
- fprintf(stderr, "libcolour: invalid encoding type\n");
- abort();
- }
+ rgb_decode(to, &from->rgb);
}
}
}
@@ -155,7 +217,7 @@ static inline double srgb_decode(double t)
t = -t;
sign = -1;
}
- t = t <= 0.040448236277380506 ? t / 12.92 : pow((t + 0.055) / 1.055, 2.4);
+ t = t <= 0.0031306684425217108 * 12.92 ? t / 12.92 : pow((t + 0.055) / 1.055, 2.4);
return t * sign;
}
generated by cgit v1.2.3-70-g09d2 (git 2.46.0) at 2024-09-19 17:07:09 +0000