@thi.ng/imago/ops/dither.js

JSON & API-based declarative and extensible image processing trees/pipelines

import { typedArray } from "@thi.ng/api";
import { ABGR8888, GRAY8, Lane, intBuffer } from "@thi.ng/pixel";
import {
  ATKINSON,
  BURKES,
  DIFFUSION_2D,
  DIFFUSION_COLUMN,
  DIFFUSION_ROW,
  FLOYD_STEINBERG,
  JARVIS_JUDICE_NINKE,
  SIERRA2,
  STUCKI,
  defBayer,
  ditherWith,
  orderedDither
} from "@thi.ng/pixel-dither";
import sharp from "sharp";
const DITHER_KERNELS = {
  atkinson: ATKINSON,
  burkes: BURKES,
  column: DIFFUSION_COLUMN,
  diffusion: DIFFUSION_2D,
  floyd: FLOYD_STEINBERG,
  jarvis: JARVIS_JUDICE_NINKE,
  row: DIFFUSION_ROW,
  sierra: SIERRA2,
  stucki: STUCKI
};
const ditherProc = async (spec, input, ctx) => {
  let { mode, num = 2, rgb = false, size = 8 } = spec;
  const [w, h] = ctx.size;
  let raw;
  if (rgb) {
    const tmp = await input.clone().ensureAlpha(1).toColorspace("srgb").raw().toBuffer({ resolveWithObject: true });
    raw = tmp.data.buffer;
    rgb = tmp.info.channels === 4;
  } else {
    raw = (await input.clone().grayscale().raw().toBuffer()).buffer;
  }
  let img = intBuffer(
    w,
    h,
    rgb ? ABGR8888 : GRAY8,
    typedArray(rgb ? "u32" : "u8", raw)
  );
  if (mode === "bayer") {
    orderedDither(img, defBayer(size), rgb ? [num, num, num] : [num]);
  } else {
    ditherWith(DITHER_KERNELS[mode], img, {
      channels: rgb ? [Lane.RED, Lane.GREEN, Lane.BLUE] : void 0
    });
  }
  if (!rgb) img = img.as(ABGR8888);
  return [
    sharp(new Uint8Array(img.data.buffer), {
      raw: {
        width: img.width,
        height: img.height,
        channels: 4
      }
    }),
    true
  ];
};
export {
  ditherProc
};