PImage img; void setup(){ img = loadImage("IMG_9103.JPG"); size(500,500); } void draw() { if(mousePressed) { // replace this chunk with a function // draw image in grayscale loadPixels(); img.loadPixels(); for(int i = 0; i < pixels.length; i++) { pixels[i] = color(brightness(img.pixels[i])); } img.updatePixels(); updatePixels(); } else { // draw image in color image(img,0,0); } }