I would like to transform one image into another by copying the pixels from pixel array to pixel array. This works just fine, but I would like to be able to see this happening. Right now I just see the end result after a while. So, how can I do some sort of an updatePixels() inside the draw() loop?

1. PImage bikeImg;
2. PImage carImg;
3. boolean firstRun = true;
4. void setup() { 
5.   size(600, 409);
6.   background(255);
7.   bikeImg = loadImage("bike.jpg");
8.   carImg = loadImage("car.jpg");
9. }
10. void draw() {
11.   if ( firstRun == true ) {
12.     firstRun = false;       
13.     // renders the initial image
14.     image(carImg, 0, 0);
15.     // loads the current screen into the pixel array
16.     loadPixels();
17.     // loads the pixels for the next image
18.     carImg.loadPixels();
19.     for (int i=0; i<bikeImg.pixels.length; i++) {     
20.       // overwrite the original image with the new one
21.       pixels[i] = bikeImg.pixels[i];
22.       updatePixels();
23.     }
24.   }
25. }