Function brightpass

pattern/canvas.js:3149–3155

(img, threshold)

}

function brightpass(img, threshold) {
    /* Returns a new image where pixels whose luminance fall below the threshold are black.
     */
    return filter(img, function(p) {
        return (Math.dot(p, LUMINANCE) > ((threshold || threshold == 0)? threshold : 0.5))? p : [0,0,0, p[3]];
    });    
}

function blur(img, radius) {
    /* Applies a stack blur filter to the image and returns the blurred image.