/**
 *  Experiments with edge detection, D. Parson, May 2017.
 *  See https://processing.org/examples/edgedetection.html,
 *  https://processing.org/reference/filter_.html
**/
                    //<>//
PImage img ;

void setup() { 
  size(1500, 1000, P2D);
  frameRate(16);
  // fullScreen(P2D);
  background(0);
}
void draw() {
  if (img == null) {
    img = loadImage("stone5152x3864.JPG"); // Load the original image
    // img = loadImage("Hex306090B.png"); 
    img.resize(width, height);
    // img.filter(INVERT);
  }
  // FILTERING HERE CHANGES THE ACTUAL PImage img.filter(POSTERIZE, (frameCount % 18)+2);
  if (random(0,100) < 50) {
    img.filter(ERODE);
  } else {
    img.filter(DILATE);
  }
  image(img, 0, 0, width, height);
  // filter(BLUR, constrain(16 - abs(32-pframenum), 0, 16));
  //filter(POSTERIZE, (frameCount % 18)+2); // filter() here filters the entire display so far
  // filter(GRAY);
  // filter(THRESHOLD, 0.5);
  // filter(ERODE);  // Just one application of ERODE or DILATE don't make much change.
  // But if you apply them repeatedly to the PImage, change is incremental
  // filter(INVERT);
  // filter(BLUR,10);
  println("frameRate = " + frameRate);
}