kernel Sepia
<   nameSpace: "popforge::ImageProcessing";
    vendor: "joa ebert";
    version: 1;
    description: "a real sepia using y transform";
>
{
    void evaluatePixel(in image3 source, out pixel3 result)
    {
        pixel3 color = sampleLinear( source, outCoord() );
        float y = 0.299 * color.r + 0.587 * color.g + 0.114 * color.b;
        
        // use min/max instead of if's
        float r = min(1.0,y + 0.19);
        float g = max(0.0,y - 0.055);
        float b = max(0.0,y - 0.22);
        
        result = pixel3(r,g,b);
    }
}