Roya

Roya is a small low-level image comparison library.

Inspired by pixelmatch with more bells and whistles.

Installation

using yarn

yarn add roya

using npm

npm i -S roya

API

roya(img1, img2, [, options])

img1, img2 — Image data of type Buffer of the images to compare

options Optional object options with the following properties:

| Property | Description | Default | | -------------- | -------------------------------------------------------------------------------------------------------------- | ----------- | | threshold | Matching threshold, ranges from 0 to 1. Smaller values make the comparison more sensitive | 0.1 | | highlightFade | Highlight color intensity will depend on the pixel ditance value | true | | highlightColor | The used highlight color, should be an array of [R,G,B] values | [255, 0, 0] | | transparent | Whether to keep the original image ot to use a blank convas to highlight the diff | false | | overlapse | Whether to use the highlight color or use the changing pixel itself | false | | method | Matching and diffing method to be used, should be one of the available methods, rgb, rgbTuned, yiq or yiqTuned | 'rgb' |

P.S. rgb method is the fastest but it might not be the best for your usecase, try the others method and pick the right one for you.

Example:

| img1 | img2 | | ------------------------------- | ------------------------------- | | | |

| options | result | | ---------------------------------------------- | ------------------------------------------------ | | undefined | | | { threshold: 0.5 } | | | { highlightColor: [255, 255, 0] } | | | { highlightFade: false } | | | { transparent: true, highlightFade: false } | | | { overlapse: true, transparent: true } | | | | | { method: 'rgb', highlightFade: false } | | | { method: 'rgbTuned', highlightFade: false } | | | { method: 'yiq', highlightFade: false } | | | { method: 'yiqTuned', highlightFade: false } | |

Usage

const fs = require('fs')
const PNG = require('pngjs').PNG
const roya = require('roya')

var img1 = fs
  .createReadStream('img1.png')
  .pipe(new PNG())
  .on('parsed', parsed)

var img2 = fs
  .createReadStream('img2.png')
  .pipe(new PNG())
  .on('parsed', parsed)

let done = 0
function parsed() {
  done++
  if (done < 2) return
  const out = roya(img1.data, img2.data)

  const diff = new PNG({ width: img1.width, height: img1.height })

  diff.data = out.data

  diff
    .pack()
    .pipe(fs.createWriteStream('diff.png'))
    .on('finish', () => console.log('done'))
}

P.S. image dimensions must be equal.