sketch_jul14a.pde

// image instance
PImage img;	

// set up canvas
void setup() {
  img = loadImage("IMG_0472.png");
  size(img.width, img.height); // this is cool!
}

/**
 * Brightness Negative
 * This will create a negative of a picture,
 * remaining all colours instead of negating
 * them too.
 */

void draw() {
  background(0);
  image(img, 0, 0); // draw the picture

  // get size & set colour mode
  int sizeImage = width * height;

  loadPixels(); // get the pixels!
  for (int i = 0; i < sizeImage; i++) {
    colorMode(RGB, 255);
    // for every pixel: get RGB values
    float r = red(pixels[i]);
    float g = green(pixels[i]);
    float b = blue(pixels[i]);
    // set brightness negative
    pixels[i] = color(255-r, 255-g, 255-b);

    colorMode(HSB, 255);
    // for every pixel: get HSB values
    float h = hue(pixels[i]);
    float s = saturation(pixels[i]);
    float v = brightness(pixels[i]);
    pixels[i] = color((255+h+127)%255, s, v);
  }
  updatePixels(); // show the pixels!
}