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@mairod
Last active October 14, 2024 08:33
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Optimised Hue shift function in GLSL
vec3 hueShift( vec3 color, float hueAdjust ){
const vec3 kRGBToYPrime = vec3 (0.299, 0.587, 0.114);
const vec3 kRGBToI = vec3 (0.596, -0.275, -0.321);
const vec3 kRGBToQ = vec3 (0.212, -0.523, 0.311);
const vec3 kYIQToR = vec3 (1.0, 0.956, 0.621);
const vec3 kYIQToG = vec3 (1.0, -0.272, -0.647);
const vec3 kYIQToB = vec3 (1.0, -1.107, 1.704);
float YPrime = dot (color, kRGBToYPrime);
float I = dot (color, kRGBToI);
float Q = dot (color, kRGBToQ);
float hue = atan (Q, I);
float chroma = sqrt (I * I + Q * Q);
hue += hueAdjust;
Q = chroma * sin (hue);
I = chroma * cos (hue);
vec3 yIQ = vec3 (YPrime, I, Q);
return vec3( dot (yIQ, kYIQToR), dot (yIQ, kYIQToG), dot (yIQ, kYIQToB) );
}
@MikeKotys
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Will it work with sRGB color format, or should I convert my color to RGB before using this function?

@arthurfisher
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My version of hue shift I did for some codegolf shader.

vec3 h(vec3 c, float s){  
    return c * mat3(c = .66 * cos(s + vec3(0, 2.09, 4.18)) + .33, c.zxy, c.yzx);
}

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