PImage input;
boolean[][] edge;
int[] pix;
float cutoff = 0.0135;
String file = "in4.jpg";

void setup() {
  input = loadImage(file);
  int w = 500;
  size(w, int(w*(input.height/(input.width + 0f))));
  input.loadPixels();
  pix = input.pixels;
  edge = new boolean[input.width][input.height];
  checkHoriz(input, 2);
  checkVert(input, 2);
  //checkHoriz(input,4);
  //checkVert(input,4);
  //checkHoriz(input,8);
  //checkVert(input,8);
  //checkHoriz(input, 10);
  //checkVert(input, 10);
  noLoop();
  draw();
}

void draw() {
  PGraphics g = createGraphics(input.width, input.height);
  g.loadPixels();
  for (int x = 0; x < g.width; x ++) {
    for (int y = 0; y < g.height; y ++) {
      if (edge[x][y]) g.pixels[y*g.width+x] = color(0);
      else g.pixels[y*g.width+x] = color(255);
    }
  }
  g.updatePixels();
  image(g, 0, 0, width, height);
}

void keyReleased(){
  if(key == ' '){
    save("out/" + file);
  }
}

void checkHoriz(PImage image, int z) {
  int w = z;
  int h = z;
  // size of rect = 2w * h
  for (int x = 0; x < image.width; x += w) {
    for (int y = 0; y < image.height; y += h) {
      if (edge(x, y, w, h, w, 0)) {
        put(edge, x, y, w, h, true);
      }
    }
  }
}

void checkVert(PImage image, int z) {
  int w = z;
  int h = z;
  // size of rect = 2w * h
  for (int x = 0; x < image.width- w; x += w) {
    for (int y = 0; y < image.height-h; y += h) {
      if (edge(x, y, w, h, 0, h)) {
        put(edge, x, y, w, h, true);
      }
    }
  }
}

void put(boolean[][] b, int x, int y, int w, int h, boolean c) {
  for (int ix = x; ix < x + w; ix ++) {
    for (int iy = y; iy < y + h; iy ++) {
      if (ix < 0 || iy < 0 || ix >= b.length || iy >= b[ix].length) continue;
      b[ix][iy] = true;
    }
  }
}

boolean edge(int x, int y, int w, int h, int iw, int ih) {
  int[] avg = avg(x, y, w, h);
  int[] avg1 = avg(x+iw, y+ih, w, h);
  float tf = 0;
  for (int i = 0; i < avg.length; i ++) {
    int d = abs(avg[i]-avg1[i]);
    float f= d/(256.0*3);
    tf += f;
    if (f >= 1) println(f);
    if (f > cutoff) return true;
  }
  return false;
  //return tf > cutoff*w*h;
}

int[] avg(int x, int y, int w, int h) {
  int r = 0;
  int g = 0;
  int b = 0;
  int n = w*h;
  for (int ix = x; ix < x + w; ix ++) {
    for (int iy = y; iy < y + h; iy ++) {
      if (ix <= 0 || iy <= 0 || ix >= input.width || iy >= input.height) continue;
      int c = pix[iy*input.width+ix];
      r += red(c);
      g += green(c);
      b += blue(c);
    }
  }
  return new int[] {
    r/n, g/n, b/n
  };
}