saturation.metal

kernel void saturation(
                       texture2d<float, access::write> outTex [[texture(0)]],
                       texture2d<float, access::read> inTex [[texture(1)]],
                       uint2 gid [[thread_position_in_grid]]) {
    //HIGH: More than 1, LOW: Less than 1
    float filterLevel = 1.1;
    float4 c = inTex.read(gid).rgba;
    float3 hsv = rgb2hsv(c.rgb);
    hsv[1] = hsv[1] * filterLevel;
    c.rgb = hsv2rgb(hsv);
    outTex.write(c.rgba, gid);
}