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RGB / CMYK conversion in GLSL
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// From the book: Graphics Shaders | |
vec3 CMYKtoRGB (vec4 cmyk) { | |
float c = cmyk.x; | |
float m = cmyk.y; | |
float y = cmyk.z; | |
float k = cmyk.w; | |
float invK = 1.0 - k; | |
float r = 1.0 - min(1.0, c * invK + k); | |
float g = 1.0 - min(1.0, m * invK + k); | |
float b = 1.0 - min(1.0, y * invK + k); | |
return clamp(vec3(r, g, b), 0.0, 1.0); | |
} | |
vec4 RGBtoCMYK (vec3 rgb) { | |
float r = rgb.r; | |
float g = rgb.g; | |
float b = rgb.b; | |
float k = min(1.0 - r, min(1.0 - g, 1.0 - b)); | |
vec3 cmy = vec3(0.0); | |
float invK = 1.0 - k; | |
if (invK != 0.0) { | |
cmy.x = (1.0 - r - k) / invK; | |
cmy.y = (1.0 - g - k) / invK; | |
cmy.z = (1.0 - b - k) / invK; | |
} | |
return clamp(vec4(cmy, k), 0.0, 1.0); | |
} | |
void mainImage( out vec4 fragColor, in vec2 fragCoord ) | |
{ | |
vec2 uv = fragCoord.xy / iResolution.xy; | |
vec3 rgbColor = texture(iChannel0, vec2(uv.x, 1. - uv.y)).rgb; | |
vec4 cmykColor = RGBtoCMYK(rgbColor); | |
vec3 rgbProof = CMYKtoRGB(cmykColor); | |
fragColor = vec4(rgbProof.xyz,1.0); | |
// fragColor = vec4(rgbColor,1.0); | |
} |
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