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import { Color } from "../../deps/color.ts";import { findClosestColor } from "../util/closest.ts";
/** * Dither the image into a smaller palette * Uses two-row Sierra matrix */export function sierra2(  pixels: Color[],  width: number,  palette: Color[],): Color[] {  let i = 0;  // pixels is an array of pixels with r, g, b values  // width is the width of the image in pixels  while (i < (pixels.length)) {    const newC = findClosestColor(pixels[i], palette);    const err = {      r: Math.floor((pixels[i].r - newC.r) / 16),      g: Math.floor((pixels[i].r - newC.g) / 16),      b: Math.floor((pixels[i].r - newC.b) / 16),    };
    // Match our quantized palette    pixels[i] = newC;
    // Spread error to neighbouring pixels    if (i < pixels.length - 1) {      // Spread error to next pixel      pixels[i + 1].r += err.r * 4;      pixels[i + 1].g += err.g * 4;      pixels[i + 1].b += err.b * 4;      if (i < pixels.length - 2) {        // Spread error to next pixel        pixels[i + 2].r += err.r * 3;        pixels[i + 2].g += err.g * 3;        pixels[i + 2].b += err.b * 3;        // Spread error to lower pixels        if (i < pixels.length - width - 2) {          pixels[i + width - 2].r += err.r;          pixels[i + width - 1].r += err.r * 2;          pixels[i + width].r += err.r * 3;          pixels[i + width + 1].r += err.r * 2;          pixels[i + width + 2].r += err.r;
          pixels[i + width - 2].g += err.g;          pixels[i + width - 1].g += err.g * 2;          pixels[i + width].g += err.g * 3;          pixels[i + width + 1].g += err.g * 2;          pixels[i + width + 2].g += err.g;
          pixels[i + width - 2].b += err.b;          pixels[i + width - 1].b += err.b * 2;          pixels[i + width].b += err.b * 3;          pixels[i + width + 1].b += err.b * 2;          pixels[i + width + 2].b += err.b;        }      }    }    i += 1;  }  return pixels;}
/** * Dither the image into a smaller palette * Uses Sierra lite matrix * Use twoRowSierraDither for more accuracy */export function sierraLite(  pixels: Color[],  width: number,  palette: Color[],): Color[] {  let i = pixels.length - 1;  // pixels is an array of pixels with r, g, b values  // width is the width of the image in pixels  while (i >= 0) {    const newC = findClosestColor(pixels[i], palette);    const err = {      r: Math.floor((pixels[i].r - newC.r) >> 2),      g: Math.floor((pixels[i].r - newC.g) >> 2),      b: Math.floor((pixels[i].r - newC.b) >> 2),    };
    // Match our quantized palette    pixels[i] = newC;
    // Spread error to neighbouring pixels    if (i > 0) {      // Spread error to next pixel      if (i % width !== 0) {        pixels[i - 1].r += err.r << 1;        pixels[i - 1].g += err.g << 1;        pixels[i - 1].b += err.b << 1;      }      // Spread error to lower pixels      if (i > width + 1) {        pixels[i - width + 1].r += err.r;        pixels[i - width].r += err.r;        pixels[i - width + 1].g += err.g;        pixels[i - width].g += err.g;        pixels[i - width + 1].b += err.b;        pixels[i - width].b += err.b;      }    }    i -= 1;  }  return pixels;}