PImage mine, fog;
int i = 0;
int srcw=700;
int srch=474;
int wid=400;
int hi=400;
color c, cprime;

void setup( ) {
  size(srcw, srch);
  mine = loadImage("mine.jpg");
  fog = loadImage("fog.jpg");
  image(fog,0,0);
  for (int i=0; i<srcw; i++){
    for(int j=0; j<srch; j++) {
      c = get(i,j);
      if (i<wid && j<hi) {
        cprime=mine.get(i,j);
        cprime=color(4*(int(red(c))/4) + (int(red(cprime))/64),
                     4*(int(green(c))/4) + (int(green(cprime))/64),
                     4*(int(blue(c))/4) + (int(blue(cprime))/64));
        set(i,j, cprime);
      } else {
        set(i,j,c);
      }
    }
  }
 }
 
 void draw( ) {
   if (mousePressed) {
     saveFrame("labFog.png");
   }
 }