Image Difference

diff.js

const util = require('util');
const sharp = require('sharp');
const imageDiff = require('native-image-diff');
const sizeOf = require('buffer-image-size');
const jpeg = require('jpeg-js');
const fs = require('fs');
const read = util.promisify(fs.readFile);

const files = ['./original1.jpg', './original2.png', './original3.jpg', './original4.png', './alternate4.png'];

async function compare() {
	for (let i = 0; i < files.length; i++) {
		console.log('-------------------------------');
		console.log(`Image #${i + 1}`);
		console.time(`Image #${i + 1}`);

		const toCompare = await sharp(await read(files[i]))
			.resize(2000, 2000)
			.max()
			.withoutEnlargement()
			.background({ r: 255, g: 255, b: 255, alpha: 1 })
			.flatten()
			.jpeg({ quality: 92 })
			.toBuffer();

		const { width, height } = sizeOf(toCompare);

		for (let f = 1; f < 5; f++) {
			const file = await read(`./saved${f}.jpg`);

			const { width: fWidth, height: fHeight } = sizeOf(file);
			if (height !== fHeight || width !== fWidth)
				continue;

			const data = imageDiff.diffImages({
				image1: jpeg.decode(toCompare),
				image2: jpeg.decode(file),
				generateDiffImage: false
			});

			console.log(`	Diff for saved #${f}: ${data.pixels.toLocaleString()}px, delta ${data.totalDelta.toLocaleString()}, ${(data.pixels / (width * height) * 100).toFixed(4)}%`);
		}
		console.timeEnd(`Image #${i + 1}`);
	}
}

compare();