noStroke();
frameRate(0);
var draw = function() {
    if (!this.loadPixels) { return; }
    this.loadPixels();
    var pix=this.imageData.data; // canvas pixels
    
    var block = 4; // block-size
    
    for (var x = 0; x < 400; x+= block) {
        for (var y = 0; y < 400; y+=block) {
            var p = noise(x/100, y/100, frameCount/10)*255;
            
            for(var xx = x; xx < x + block; xx++) {
                for(var yy = y; yy < y + block; yy++) {
                    pix[yy*1600+xx*4] = p; // assign noise to red part of pixel
                    pix[yy*1600+xx*4+1] = p; // assign noise to g part of pixel
                    pix[yy*1600+xx*4+2] = p; // assign noise to b part of pixel
                }
            }
        }
    } 
    
    this.updatePixels(); // assign new pixels to canvas
};