+ if (source_curve == GAMMA_sRGB) {
+ for (unsigned i = 0; i < EXPANSION_CURVE_SIZE; ++i) {
+ float x = i / (float)(EXPANSION_CURVE_SIZE - 1);
+ if (x < 0.04045f) {
+ expansion_curve[i] = (1.0/12.92f) * x;
+ } else {
+ expansion_curve[i] = pow((x + 0.055) * (1.0/1.055f), 2.4);
+ }
+ }
+ invalidate_1d_texture("expansion_curve_tex");
+ return read_file("gamma_expansion_effect.frag");
+ }
+ if (source_curve == GAMMA_REC_709 || // Also includes Rec. 601, and 10-bit Rec. 2020.
+ source_curve == GAMMA_REC_2020_12_BIT) {
+ // Rec. 2020, page 3.
+ float alpha, beta;
+ if (source_curve == GAMMA_REC_2020_12_BIT) {
+ alpha = 1.0993f;
+ beta = 0.0181f;
+ } else {
+ alpha = 1.099f;
+ beta = 0.018f;
+ }
+ for (unsigned i = 0; i < EXPANSION_CURVE_SIZE; ++i) {
+ float x = i / (float)(EXPANSION_CURVE_SIZE - 1);
+ if (x < beta * 4.5f) {
+ expansion_curve[i] = (1.0/4.5f) * x;
+ } else {
+ expansion_curve[i] = pow((x + (alpha - 1.0f)) / alpha, 1.0f/0.45f);
+ }
+ }
+ invalidate_1d_texture("expansion_curve_tex");
+ return read_file("gamma_expansion_effect.frag");
+ }
+ assert(false);