util_img.js

const pixelmatch = require('pixelmatch');

// 0.1 means 10% of the pixels can differ and the images are still equal
const IS_EQUAL_THRESHOLD = 0.1;

/**
 * Compares 2 images by counting the no of differing pixels
 * @param {*} img1
 * @param {*} img2
 */
const isEqual = (img1, img2) => {
  // Images with different sizes are not equal
  if (img1.height !== img2.height) return false;
  if (img1.width !== img2.width) return false;

  const diffPixels = pixelmatch(img1.data, img2.data, diff.data, img1.width, img1.height, {
    threshold: 0.1, // That's the default threshold
  });
  const totalPixels = img1.width * img1.height;
  const maxDiffPixels = totalPixels * IS_EQUAL_THRESHOLD;
  return (diffPixels < maxDiffPixels);
};

const imageArrayIncludesImage = (imageArray, img) => {
  for (i = 0; i < imageArray.length; i++) {
    if (isEqual(img, imageArray[i])) return true;
  } 
  return false;
};

exports = {
  isEqual,
  imageArrayIncludesImage,
};