/*
 * This version of grayscaling is based on taking uniform
 * average of red,green,blue for each pixel. Unfortunately,
 * such an average is not very pleasing.
 *
 * See grayscale_luminosity for better approach.
 */

PImage slu;
int w,h;

void setup() {
  size(408,300);  // take advantage of our knowledge of the size

// Can either load an image stored locally, as follows:
//  slu = loadImage("campus4.jpg");
// Or can load an image from a URL as follows:
  slu = loadImage("http://business.slu.edu/uploads/2012/11/08/slu-homepage-campus4.jpg");

  w = slu.width;
  h = slu.height;

  for (int x=0; x < w; x++) {
    for (int y=0; y < h; y++) {
      color c = slu.get(x,y);
      float gray = (red(c) + green(c) + blue(c))/3;  // divide sum by 3 to average
      color replace = color(gray);
      slu.set(x,y,replace);
    }
  }

  // time to display it
  image(slu, 0, 0);
}