Function threshold

plugins/plugin-threshold/src/index.ts:30–55

* Applies a minimum color threshold to a grayscale image. * Converts image to grayscale by default. * @example * ```ts * import { Jimp } from "jimp"; * * const image = await Jimp.read("test/image.png"); * * image.threshold({ max: 150 }); * ```

(image: I, options: ThresholdOptions)

   * ```
   */
  threshold<I extends JimpClass>(image: I, options: ThresholdOptions) {
    let {
      max,
      replace = 255,
      // eslint-disable-next-line prefer-const
      autoGreyscale = true,
    } = ThresholdOptionsSchema.parse(options);

    max = limit255(max);
    replace = limit255(replace);

    if (autoGreyscale) {
      color.greyscale(image);
    }

    image.scan((_, __, idx) => {
      const grey =
        image.bitmap.data[idx]! < max ? image.bitmap.data[idx]! : replace;

      image.bitmap.data[idx] = grey;
      image.bitmap.data[idx + 1] = grey;
      image.bitmap.data[idx + 2] = grey;
    });

    return image;
  },
};