--- /dev/null
+// 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;
+}