Bad TV image reception: Black & White and Colour version

probabilistic_dithering_noiseImage.pde

//based on https://www.reddit.com/r/processing/comments/lgcy90/probabilistic_dithering/
PImage img;
int w, h;
boolean colour = false;
void keyPressed() {
  if (key == 'C' || key == 'c') {
    if (colour) colour = false;
    else colour = true;
  }
}
void settings() {
  img=loadImage("cat.jpg");
  size(w=img.width, h=img.height);
  println("w="+w+", h="+h);
}
void setup() {
  noStroke();
  fill(0, 50);
}
void draw() {
  background(255);
  
  if (colour) {
    tint(255, 100);
    image(img, 0, 0);
    fill(0, 20);
  } else fill(0, 50);
  
  for (int y = 0; y < height; y+=2) {
    for (int x = 0; x < width; x+=2) {
      color c = img.get(x, y);
      float b = brightness(c);
      float p = random(256);
      if (b <= p) rect(x, y, 4, 4);
    }
  }
  image(this.get(), random(3), 0);
}