masked_sort.pde

final float brightness = 200;

void setup() {
  noLoop();

  PImage img, mask;
  img = loadImage("img.jpg");
  mask = loadImage("mask.jpg");
  img.loadPixels();
  mask.loadPixels();
  PImage sorted1 = sortRows(img, mask);
  sorted1.loadPixels();
  PImage sorted2 = sortColumns(sorted1, mask);
  sorted2.updatePixels();
  sorted2.save("sorted-rows-columns.jpg");
  exit();
}

PImage sortColumns(PImage img, PImage mask) {
  for (int x = 0; x < img.width; x++) {
    int start = getStartColumn(x, 0, mask);
    while (start < img.height) {
      int end = getEndColumn(x, start, mask);
      int sortLength = end - start;
      color[] unsorted = new color[sortLength];
      for(int i = 0; i < sortLength; i++) {
        unsorted[i] = img.pixels[(start + i) * img.width + x];
      }
      color[] sorted = sort(unsorted);
      for(int i = 0; i < sortLength; i++) {
        img.pixels[(start + i) * img.width + x] = sorted[i];
      }
      start = getStartColumn(x, end + 1, mask);
    }
  }
  return img;
}

PImage sortRows(PImage img, PImage mask) {
  for (int y = 0; y < img.height; y++) {
    int start = getStartRow(y, 0, mask);
    while (start < img.width) {
      int end = getEndRow(y, start, mask);
      int sortLength = end - start;
      color[] unsorted = new color[sortLength];
      for(int i = 0; i < sortLength; i++) {
        unsorted[i] = img.pixels[y * img.width + (start + i)];
      }
      color[] sorted = sort(unsorted);
      for(int i = 0; i < sortLength; i++) {
        img.pixels[y * img.width + (start + i)] = sorted[i];
      }
      start = getStartRow(y, end + 1, mask);
    }
  }
  return img;
}

int getStartColumn(int col, int start, PImage mask) {
  for (int i = start; i < mask.height; i++) {
    if (brightness(mask.pixels[i * mask.width + col]) > brightness) {
      return i;
    }
  }
  return start;
}

int getEndColumn(int col, int start, PImage mask) {
  for (int i = start; i < mask.height; i++) {
    if (brightness(mask.pixels[i * mask.width + col]) < brightness) {
      return i;
    }
  }
  return mask.height - 1;
}

int getStartRow(int row, int start, PImage mask) {
  for (int i = start; i < mask.width; i++) {
    if (brightness(mask.pixels[row * mask.width + i]) > brightness) {
      return i;
    }
  }
  return start;
}

int getEndRow(int row, int start, PImage mask) {
  for (int i = start; i < mask.width; i++) {
    if (brightness(mask.pixels[row * mask.width + i]) < brightness) {
      return i;
    }
  }
  return mask.width - 1;
}