Replace broken images with noise

noized.js

HTMLCanvasElement.prototype.addNoise = function(r, g, b, a, l) {
    // default variables: red, green, blue, alpha, light
    a||(a=-.4);
    l||(l=.5);
    //(!red&&green)||(alpha=green,green=128);
    //(!green&&blue)||(brightness=blue,blue=128);
    r||(r=1);
    g||(g=1);
    b||(b=1);
   
    r*=255;
    g*=255;
    b*=255;
    a+=.5;
    l*=255;
    
    var ctx = this.getContext('2d');

    var imageData = ctx.getImageData(0, 0, this.width, this.height),
        pixels = imageData.data;
     
    for (var i = 0, il = pixels.length; i < il; i += 4) {
        // pixel of noize generation
        var color = Math.random() * l;

        // alpha-composition
        !pixels[i]&&pixels[i]!=0    ||(pixels[i]  =pixels[i]  +(!pixels[i]||128)  *color/r*a+pixels[i]  *(1 - a));
        !pixels[i+1]&&pixels[i+1]!=0||(pixels[i+1]=pixels[i+1]+(!pixels[i+1]||128)*color/g*a+pixels[i+1]*(1 - a));
        !pixels[i+2]&&pixels[i+2]!=0||(pixels[i+2]=pixels[i+2]+(!pixels[i+2]||128)*color/b*a+pixels[i+2]*(1 - a));
        !pixels[i+3]&&pixels[i+3]!=0||(pixels[i+3]=pixels[i+3]+(!pixels[i+2]||128)*color/a*a+pixels[i+3]*(1 - a));
    } 
    ctx.putImageData(imageData, 0, 0);
    return this;
};

HTMLImageElement.prototype.addNoise = function(r, g, b, a, l){    
    var c=document.createElement('canvas'),e=this;
    c.width = e.width||100;
    c.height = e.height||100;
    var ctx=c.getContext("2d");
    // ctx.font="30px Arial";
    e.alt||ctx.fillText(e.alt,10,(e.height/2)-15);
    c.addNoise(r, g, b, a, l);
    e.src = c.toDataURL();
    return e;
};

(function(m){
    for(i in m){
        // is number or zero
        !((i*1||i==0)&&m[i])||m[i].addNoise();
    }
})(document.getElementsByTagName('img'));