PImage img, img2, img3, img4;

void setup() {
  size(530, 363);  
  
  // load images
  // 1st
  img = loadImage("logo.png");
  image(img, 10, 10); 
  // 2nd
  img2 = img.get();
  image(img2, 2*10+1*img.width, 10);
  // 3rd
  img3 = img.get();
  image(img3, 1*10, 2*10+img.height);
  // 4rd
  img4 = img.get();
  image(img4, 2*10+1*img.width, 2*10+img.height);
  
  noLoop();
}

void draw() {
  // colourize 1st pic
  color co1;
  color cn1 = color(random(255),random(255),random(255));
  co1 = get(10,10);
  for(int x=10; x<260; x = x + 1) {
    for(int y=10; y<177; y = y + 1) {
      if (get(x,y) == co1) {
        set(x,y, cn1); 
      } else {
        set(x, y, color(255-red(cn1), 255-green(cn1), 255-blue(cn1)));
      }
    }
  }
  
  // colourize 2nd pic
  color co2;
  color cn2 = color(random(255),random(255),random(255));
  co2 = get(2*10+img.width,10);
  for(int x=2*10+img.width; x<520; x = x + 1) {
    for(int y=10; y<177; y = y + 1) {
      if (get(x,y) == co2) {
        set(x,y, cn2); 
      } else {
        set(x, y, color(255-red(cn2), 255-green(cn2), 255-blue(cn2)));
      }
    }
  }
  
  // colourize 3rd pic
  color co3;
  color cn3 = color(random(255),random(255),random(255));
  co3 = get(10, 2*10+img.height);
  for(int x=10; x<260; x = x + 1) {
    for(int y=2*10+img.height; y<354; y = y + 1) {
      if (get(x,y) == co3) {
        set(x,y, cn3); 
      } else {
        set(x, y, color(255-red(cn3), 255-green(cn3), 255-blue(cn3)));
      }
    }
  }
  
  // colourize 4rd pic
  color co4;
  color cn4 = color(random(255),random(255),random(255));
  co4 = get(2*10+img.width, 2*10+img.height);
  for(int x=2*10+img.width; x<520; x = x + 1) {
    for(int y=2*10+img.height; y<354; y = y + 1) {
      if (get(x,y) == co4) {
        set(x,y, cn4); 
      } else {
        set(x, y, color(255-red(cn4), 255-green(cn4), 255-blue(cn4)));
      }
    }
  }
}

void keyPressed() {
  if (keyCode == KeyEvent.VK_SPACE) {
    redraw();
  }
}