code: function dither(cb) {
    const rgb565Matrix = [1, 9, 3, 11, 13, 5, 15, 7, 4, 12, 2, 10, 16, 8, 14, 6];
    this.scanQuiet(0, 0, this.bitmap.width, this.bitmap.height, function(
      x,
      y,
      idx
    ) {
      const thresholdId = ((y & 3) << 2) + (x % 4);
      const dither = rgb565Matrix[thresholdId];
      this.bitmap.data[idx] = Math.min(this.bitmap.data[idx] + dither, 0xff);
      this.bitmap.data[idx + 1] = Math.min(
        this.bitmap.data[idx + 1] + dither,
        0xff
      );
      this.bitmap.data[idx + 2] = Math.min(
        this.bitmap.data[idx + 2] + dither,
        0xff
      );
    });
  
    if (isNodePattern(cb)) {
      cb.call(this, null, this);
    }
  
    return this;
  }
docs: Apply a ordered dithering effect
  @param {function(Error, Jimp)} cb (optional) a callback for when complete
  @returns {Jimp} this for chaining of methods