// Original Code from Linus Persson, phlp.info

void setup(){
size(300,300);
frameRate(30);
}

void draw() {
 loadPixels();
 for(int x = 0; x<width/2; x++) {
   for(int y = 0; y<height/2; y++) {
     int x_new = 2*x+int(random(2));
     int y_new = 2*y+int(random(2));

     if (x_new < width && y_new < height) {
       int dest_pixel = (y_new*width + x_new);

       color c = pixels[y*width+x];

       if(c == #FFFFFF){
         pixels[dest_pixel] = #000000;
       }
       else {
         pixels[dest_pixel] = #FFFFFF;
       }
     }
   }
 }
 updatePixels();
}