Prepare for three channels STF

shaders/image.frag

@@ -1,12 +1,11 @@
 #version 330
 
 uniform sampler2D qt_Texture0;
-uniform vec3 mtf_param;
+uniform vec3 mtf_param[3];
 uniform bool bw;
 uniform bool invert;
 uniform bool srgb;
 uniform bool false_color;
-uniform vec3 whiteBalance;
 in vec2 qt_TexCoord0;
 layout(location = 0) out vec4 color;
 
@@ -17,11 +16,11 @@ vec3 Linear2sRGB(vec3 color)
                greaterThan(color, vec3(0.0031308)));
 }
 
-vec4 MTF(vec4 x, vec3 m)
+vec4 MTF(vec4 x, vec4 low, vec4 mid, vec4 high)
 {
-    x = (x - m.x) / (m.z - m.x);
+    x = (x - low) / (high - low);
     x = clamp(x, vec4(0.0), vec4(1.0));
-    return ((m.y - 1) * x) / ((2 * m.y - 1) * x - m.y);
+    return ((mid - 1) * x) / ((2 * mid - 1) * x - mid);
 }
 
 vec3 falsecolor(float color)
@@ -48,7 +47,7 @@ void main(void)
 {
     color = texture(qt_Texture0, qt_TexCoord0);
     if(bw)color = color.rrra;
-    color = MTF(color, mtf_param);
+    color = MTF(color, vec4(mtf_param[0], 0.0), vec4(mtf_param[1], 0.5), vec4(mtf_param[2], 1.0));
     if(false_color)color.rgb = falsecolor(color.r);
 
     if(invert)color.rgb = vec3(1.0) - color.rgb;
@@ -57,8 +56,6 @@ void main(void)
 
     if(srgb)color.rgb = Linear2sRGB(color.rgb);
 
-    color.rgb *= whiteBalance;
-
     if(any(lessThan(qt_TexCoord0, vec2(0.0))) || any(greaterThan(qt_TexCoord0, vec2(1.0))))
         color = vec4(0.0, 0.0, 0.0, 1.0);