/**
 * Posterise the source image and save the result in the target image.
 * Restrict the amount of used brightness levels to four equidistant values.
 *
 * @param x The x coordinate of the pixel to posterise
 * @param y The y coordinate of the pixel to posterise
 * @param source The source image data
 * @param target The image data to save the converted color information to
 * @param width The width of the canvas
 * @param height The height of the canvas
 */
export function quantisegrayscale(x: number, y: number, source: Uint8ClampedArray, target: Uint8ClampedArray, width: number, height: number) {

    // TODO: Convert the pixel at position (x, y) in the source array from RGB to XYZ. Limit the 
    // TODO: Limit the brightness to the set of 4 different values 0, 85, 170, 255.
    // TODO: Set the RGBA values in the target array to this brightness.
}