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import { isNodePattern } from "@jimp/utils";
/**
* Apply a ordered dithering effect
* @param {function(Error, Jimp)} cb (optional) a callback for when complete
* @returns {Jimp} this for chaining of methods
*/
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;
}
export default (() => ({
dither565: dither,
dither16: dither
}));
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