Implement the Rec. 709 gamma curve.

[movit] / gamma_expansion_effect_rec709.glsl

diff --git a/gamma_expansion_effect_rec709.glsl b/gamma_expansion_effect_rec709.glsl
new file mode 100644 (file)
index 0000000..00259cc
--- /dev/null
+++ b/gamma_expansion_effect_rec709.glsl
@@ -0,0 +1,31 @@
+// Expand Rec. 601/Rec. 709 gamma curve.
+
+#if 0
+
+// if we have the lut
+uniform sampler1D PREFIX(rec709_tex);
+
+vec4 FUNCNAME(vec2 tc) {
+       vec4 x = LAST_INPUT(tc);
+
+       x.r = texture1D(PREFIX(rec709_tex), x.r).x;
+       x.g = texture1D(PREFIX(rec709_tex), x.g).x;
+       x.b = texture1D(PREFIX(rec709_tex), x.b).x;
+
+       return x;
+}
+
+#else
+
+// use arithmetic (slow)
+vec4 FUNCNAME(vec2 tc) {
+       vec4 x = LAST_INPUT(tc);
+
+       vec3 a = x.rgb * vec3(1.0/4.500);
+       vec3 b = pow((x.rgb + vec3(0.099)) * vec3(1.0/1.099), vec3(1.0/0.45));
+       vec3 f = vec3(greaterThan(x.rgb, vec3(0.081)));
+
+       return vec4(mix(a, b, f), x.a); 
+}
+ 
+#endif