Function dither

plugins/plugin-dither/src/index.ts:15–36

* Apply a ordered dithering effect. * @example * ```ts * import { Jimp } from "jimp"; * * const image = await Jimp.read("test/image.png"); * * image.dither(); * ```

(image: I)

   * ```
   */
  dither<I extends JimpClass>(image: I) {
    const rgb565Matrix = [
      1, 9, 3, 11, 13, 5, 15, 7, 4, 12, 2, 10, 16, 8, 14, 6,
    ];

    image.scan((x, y, idx) => {
      const thresholdId = ((y & 3) << 2) + (x % 4);
      const dither = rgb565Matrix[thresholdId]!;

      image.bitmap.data[idx] = Math.min(image.bitmap.data[idx]! + dither, 0xff);
      image.bitmap.data[idx + 1] = Math.min(
        image.bitmap.data[idx + 1]! + dither,
        0xff,
      );
      image.bitmap.data[idx + 2] = Math.min(
        image.bitmap.data[idx + 2]! + dither,
        0xff,
      );
    });

    return image;
  },
};