It's now 2014 :-P (Happy new year!)

[movit] / gamma_expansion_effect.cpp

diff --git a/gamma_expansion_effect.cpp b/gamma_expansion_effect.cpp
index 8930b9f1d4a8ed76cdf450682970be13bbd29d10..5b5f44d64ac03086acc8db44b3e1b9e8c0b499c1 100644 (file)
--- a/gamma_expansion_effect.cpp
+++ b/gamma_expansion_effect.cpp
@@ -1,3 +1,4 @@
+#include <math.h>
 #include <assert.h>
 
 #include "gamma_expansion_effect.h"
@@ -7,18 +8,48 @@ GammaExpansionEffect::GammaExpansionEffect()
        : source_curve(GAMMA_LINEAR)
 {
        register_int("source_curve", (int *)&source_curve);
+       memset(expansion_curve, 0, sizeof(expansion_curve));
+       register_1d_texture("expansion_curve_tex", expansion_curve, EXPANSION_CURVE_SIZE);
 }
 
 std::string GammaExpansionEffect::output_fragment_shader()
 {
-       switch (source_curve) {
-       case GAMMA_LINEAR:
-               return read_file("identity.glsl");
-       case GAMMA_sRGB:
-               return read_file("gamma_expansion_effect_srgb.glsl");
-       case GAMMA_REC_709:  // and GAMMA_REC_601
-               return read_file("gamma_expansion_effect_rec709.glsl");
-       default:
-               assert(false);
+       if (source_curve == GAMMA_LINEAR) {
+               return read_file("identity.frag");
        }
+       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);
 }