From: Steinar H. Gunderson <sgunderson@bigfoot.com>
Date: Mon, 1 Oct 2012 19:01:36 +0000 (+0200)
Subject: Implement the Rec. 709 gamma curve.
X-Git-Tag: 1.0~453
X-Git-Url: https://git.sesse.net/?p=movit;a=commitdiff_plain;h=ca8d64aa3d306d31f53979ba95b3f9afdf6e4d92

Implement the Rec. 709 gamma curve.
---

diff --git a/gamma_compression_effect.cpp b/gamma_compression_effect.cpp
index 5815428..5a76ec3 100644
--- a/gamma_compression_effect.cpp
+++ b/gamma_compression_effect.cpp
@@ -17,8 +17,7 @@ std::string GammaCompressionEffect::output_glsl()
 	case GAMMA_sRGB:
 		return read_file("gamma_compression_effect_srgb.glsl");
 	case GAMMA_REC_709:  // and GAMMA_REC_601
-		// Not implemented yet.
-		assert(false);
+		return read_file("gamma_compression_effect_rec709.glsl");
 	default:
 		assert(false);
 	}
diff --git a/gamma_compression_effect_rec709.glsl b/gamma_compression_effect_rec709.glsl
new file mode 100644
index 0000000..807cd49
--- /dev/null
+++ b/gamma_compression_effect_rec709.glsl
@@ -0,0 +1,31 @@
+// Compress to Rec. 601/Rec. 709 gamma curve.
+
+#if 0
+
+// if we have the lut
+uniform sampler1D PREFIX(rec709_inverse_tex);
+
+vec4 FUNCNAME(vec2 tc) {
+	vec4 x = LAST_INPUT(tc);
+
+	x.r = texture1D(PREFIX(rec709_inverse_tex), x.r).x;
+	x.g = texture1D(PREFIX(rec709_inverse_tex), x.g).x;
+	x.b = texture1D(PREFIX(rec709_inverse_tex), x.b).x;
+
+	return x;
+}
+
+#else
+
+// use arithmetic (slow)
+vec4 FUNCNAME(vec2 tc) {
+	vec4 x = LAST_INPUT(tc);
+
+	vec3 a = vec3(4.5) * x.rgb;
+	vec3 b = vec3(1.099) * pow(x.rgb, vec3(0.45)) - vec3(0.099);
+	vec3 f = vec3(greaterThan(x.rgb, vec3(0.018)));
+
+	return vec4(mix(a, b, f), x.a); 
+}
+ 
+#endif
diff --git a/gamma_compression_effect_srgb.glsl b/gamma_compression_effect_srgb.glsl
index 2d53e08..e65d6bb 100644
--- a/gamma_compression_effect_srgb.glsl
+++ b/gamma_compression_effect_srgb.glsl
@@ -3,14 +3,14 @@
 #if 0
 
 // if we have the lut
-uniform sampler1D PREFIX(srgb_tex);
+uniform sampler1D PREFIX(srgb_inverse_tex);
 
 vec4 FUNCNAME(vec2 tc) {
 	vec4 x = LAST_INPUT(tc);
 
-	x.r = texture1D(PREFIX(srgb_tex), x.r).x;
-	x.g = texture1D(PREFIX(srgb_tex), x.g).x;
-	x.b = texture1D(PREFIX(srgb_tex), x.b).x;
+	x.r = texture1D(PREFIX(srgb_inverse_tex), x.r).x;
+	x.g = texture1D(PREFIX(srgb_inverse_tex), x.g).x;
+	x.b = texture1D(PREFIX(srgb_inverse_tex), x.b).x;
 
 	return x;
 }
diff --git a/gamma_expansion_effect.cpp b/gamma_expansion_effect.cpp
index 74a8de9..fdf34f5 100644
--- a/gamma_expansion_effect.cpp
+++ b/gamma_expansion_effect.cpp
@@ -17,8 +17,7 @@ std::string GammaExpansionEffect::output_glsl()
 	case GAMMA_sRGB:
 		return read_file("gamma_expansion_effect_srgb.glsl");
 	case GAMMA_REC_709:  // and GAMMA_REC_601
-		// Not implemented yet.
-		assert(false);
+		return read_file("gamma_expansion_effect_rec709.glsl");
 	default:
 		assert(false);
 	}
diff --git a/gamma_expansion_effect_rec709.glsl b/gamma_expansion_effect_rec709.glsl
new file mode 100644
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