X-Git-Url: https://git.sesse.net/?p=movit;a=blobdiff_plain;f=lift_gamma_gain_effect.glsl;fp=lift_gamma_gain_effect.glsl;h=17437fb246e717f985671d4970ce7d1b404056d0;hp=0000000000000000000000000000000000000000;hb=dc8b571877bef7ad65064dc05a1aeda5dba16ee6;hpb=f6c44598c9dad9ddd024c5f8f010d179a6d971fd

diff --git a/lift_gamma_gain_effect.glsl b/lift_gamma_gain_effect.glsl
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+// Standard lift/gamma/gain color correction tools.
+//
+// We do lift in a nonlinear (gamma-2.2) space since that looks a lot better
+// than in linear (blacks stay a lot closer to black). The two others don't
+// really care; they are (sans some constants) commutative with the x^2.2
+// operation.
+
+// These are calculated in the host code to save some arithmetic.
+uniform vec3 PREFIX(gain_pow_inv_gamma), PREFIX(inv_gamma_22);
+
+vec4 FUNCNAME(vec2 tc) {
+	vec4 x = LAST_INPUT(tc);
+
+	// do lift in nonlinear space (the others don't care)
+	x.rgb = pow(x.rgb, vec3(1.0/2.2));
+	x.rgb += PREFIX(lift) * (vec3(1) - x.rgb);
+	x.rgb = pow(x.rgb, PREFIX(inv_gamma_22));
+	x.rgb *= PREFIX(gain_pow_inv_gamma);
+
+	return x;
+}