Nothing fancy. Messing around with OpenCV in processing. Capture the image for a webcam and apply the Canny Edge Detection to find the edges. Had the biggest problem in shifting the fade.

PImage[] shiftKey(PImage[] arr, PImage latest) {
  for (int k=0; k<curmaxpics-1; k++) {
    arr[k] = arr[k+1];
  }
  arr[curmaxpics-1] = latest;
  return arr;
}