LYGIA Shader Library

Use:

rgb2xyz(<vec3|vec4> color)

Check it on Github

#ifndef FNC_LAB2XYZ
#define FNC_LAB2XYZ
vec3 lab2xyz(in vec3 c) {
    vec3 f = vec3(0.0);
    f.y = (c.x + 16.0) / 116.0;
    f.x = c.y / 500.0 + f.y;
    f.z = f.y - c.z / 200.0;
    vec3 c0 = f * f * f;
    vec3 c1 = (f - 16.0 / 116.0) / 7.787;
    return vec3(95.047, 100.000, 108.883) * mix(c0, c1, step(f, vec3(0.206897)));
}

vec4 lab2xyz(in vec4 c) { return vec4(lab2xyz(c.xyz), c.w); }
#endif

Use:

rgb2xyz(<float3|float4> color)

Check it on Github

#ifndef FNC_LAB2XYZ
#define FNC_LAB2XYZ
float3 lab2xyz(in float3 c) {
    float3 f = float3(0.0, 0.0, 0.0);
    f.y = (c.x + 16.0) / 116.0;
    f.x = c.y / 500.0 + f.y;
    f.z = f.y - c.z / 200.0;
    float3 c0 = f * f * f;
    float3 c1 = (f - 16.0 / 116.0) / 7.787;
    return float3(95.047, 100.000, 108.883) * lerp(c0, c1, step(f, float3(0.206897, 0.206897, 0.206897)));
}

float4 lab2xyz(in float4 c) { return float4(lab2xyz(c.xyz), c.w); }
#endif

Check it on Github

fn lab2xyz(c : vec3<f32>) -> vec3<f32> {
    var f = vec3<f32>(0.0);
    f.y = (c.x + 16.0) / 116.0;
    f.x = c.y / 500.0 + f.y;
    f.z = f.y - c.z / 200.0;
    let c0 = f * f * f;
    let c1 = (f - 16.0 / 116.0) / 7.787;
    return vec3<f32>(95.047, 100.000, 108.883) * mix(c0, c1, step(f, vec3<f32>(0.206897)));
}