jpg-url-to-minitel-grayscale-mosaic.ts

import Jimp from 'jimp';

// const imageUrl = 'https://i.scdn.co/image/ab67616d00001e02e8b066f70c206551210d902b';
// const imageUrl = 'https://i.scdn.co/image/ab67616d00001e02921f7aa6349a070b6f26b3ff';
// const imageUrl = 'https://i.scdn.co/image/ab67616d0000b2734f70220d934183ce2db16d6a';
const imageUrl = 'https://i.scdn.co/image/ab67616d00001e022eae3ae708586c21b6eee710';
const outputImagePath = './output.jpg';

type RGB = [number, number, number];
type Grayscale = number;

// Grayscale values
const grayScales: Grayscale[] = [0, 40, 50, 60, 70, 80, 90, 100];

// Function to calculate absolute difference
function colorDistance(gs1: Grayscale, gs2: Grayscale): number {
  return Math.abs(gs1 - gs2);
}

// Function to convert RGB to grayscale
function rgbToGrayscale(rgb: RGB): Grayscale {
  return (rgb[0] + rgb[1] + rgb[2]) / 3 / 255 * 100;
}

// Function to get the closest color in grayscale and convert it to RGB
function getClosestRGB(inputColor: RGB): number {
  const grayscale = rgbToGrayscale(inputColor);
  let minDistance = Infinity;
  let closestColor = null

  for (const color of grayScales) {
    const distance = colorDistance(grayscale, color);
    if (distance < minDistance) {
      minDistance = distance;
      closestColor = color;
    }
  }

  return closestColor !== null ? closestColor/100*255 : 0;
}

Jimp.read(imageUrl)
.then(image => {
  image.scan(0, 0, image.bitmap.width, image.bitmap.height, (x, y, idx) => {
    const red = image.bitmap.data[idx];
    const green = image.bitmap.data[idx + 1];
    const blue = image.bitmap.data[idx + 2];

    const rgb = getClosestRGB([red, green, blue]);
    image.bitmap.data[idx] = rgb;
    image.bitmap.data[idx + 1] = rgb;
    image.bitmap.data[idx + 2] = rgb;
  });

  return image
  .resize(40, Jimp.AUTO)
  .writeAsync(outputImagePath);
})
.catch(err => {
  console.error(err);
});