kernel FadeToHistory
<   nameSpace : "Kevin's Tutorial Filters";
    vendor : "Kevin's Filters, Inc";
    version : 1;
    description : "Fade from color to B&W to sepia";
>
{
    void
    evaluatePixel(in image4 src, out pixel4 dst)
    {
        dst = sampleNearest(src,outCoord()).rrra;
    }
}