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Shadertoy: Reduced Image Color Quality

 ·   ·  ☕ 1 min read

A Shadertoy shader that reduces the available colors to draw with. This demo reduces the normal range of colors per channel from 256 down to just 8 by using effectively separating each colors floating point value into different categories.

// The number of available color levels per color channel.
// 4 means: 0, 0.25, 0.5, 0.75, 1.0 are options.
const float imageFactor = 8.0;

void mainImage( out vec4 fragColor, in vec2 fragCoord )
{
    // Normalized pixel coordinates (from 0 to 1)
    vec2 uv = fragCoord / iResolution.xy;

    // Time varying pixel color
    vec3 col = textureLod(iChannel0, uv, 0.0).rgb; //0.5 + 0.5*cos(iTime+uv.xyx+vec3(0,2,4));

    // Reduce the input color so each channel may only have 1 of 4 levels
    
    col = floor(col * imageFactor) / imageFactor;
    
    // Output to screen
    fragColor = vec4(col,1.0);
}

This effect might be useful for recreating an older type of video footage or simulating some form of corruption.


Sam Wronski
WRITTEN BY
Sam Wronski
Maker of things, currently helping build cloud things @ Google. World of Zero is a personal project disconnected from my professional work. Lets make something awesome together!