Hi everyone. I'm new to Processing and I'm desperate for help. 

I need help with changing image colors by looping through each pixel. I can't use tint(). Basically, I need to color all the green pixels red, and all the red pixels green in response to a mouse click.

Your help will be much appreciated.

2. PImage img;
3. 
   
4. void setup() {
5.   img = loadImage("img.jpg");
6.   size(img.width,img.height);
7. }
8. 
   
9. void draw() {
10.   loadPixels(); 
11.   img.loadPixels(); 
12.   for (int y = 0; y < height; y++) {
13.     for (int x = 0; x < width; x++) {
14.       int loc = x + y*width;
15.       
16.       // The functions red(), green(), and blue() pull out the 3 color components from a pixel.
17.       float r = red(img.pixels[loc]);
18.       float g = green(img.pixels[loc]);
19.       float b = blue(img.pixels[loc]);
20.       
21.       // Image Processing would go here
22. 
    
23.       // Set the display pixel to the image pixel
24.       pixels[loc] =  color(r,g,b);          
25.     }
26.   }
27.   updatePixels();
28. }