## Rembrandt.JS - Client- and server-side image comparison library
Rembrandt.JS is a image comparison library that works both with the
HTML5 Canvas2D API as well as the drop-in Node.JS replacement
`node-canvas`.
We created Rembrandt.JS to have an easy-to-use image comparison
library for our internal tests for [PhotoEditorSDK](https://www.photoeditorsdk.com/?utm_campaign=Projects&utm_source=Github&utm_medium=Side_Projects&utm_content=Rembrandt&utm_term=HTML5).
Go check it out. It's really awesome. :)
### Installation
#### Node.JS
Please follow the installation instructions over at [node-canvas](https://github.com/Automattic/node-canvas#installation)
in order to correctly install all required system libraries. Afterwards, just run:
`npm install rembrandt`
#### Browser
Download the latest build from our [Releases page](https://github.com/imgly/rembrandt/releases), then
include it like this:
```html
```
The `Rembrandt` JavaScript variable is now globally available.
#### Using module bundlers like Webpack etc.
Install Rembrandt via `npm install rembrandt`, then require it inside your JavaScript like so:
```js
var Rembrandt = require('rembrandt/build/browser')
```
### Usage
Here is an example (ES6 / ES2015):
```js
import Rembrandt from 'rembrandt'
const rembrandt = new Rembrandt({
// `imageA` and `imageB` can be either Strings (file path on node.js,
// public url on Browsers) or Buffers
imageA: '/path/to/imageA',
imageB: fs.readFileSync('/path/to/imageB'),
// Needs to be one of Rembrandt.THRESHOLD_PERCENT or Rembrandt.THRESHOLD_PIXELS
thresholdType: Rembrandt.THRESHOLD_PERCENT,
// The maximum threshold (0...1 for THRESHOLD_PERCENT, pixel count for THRESHOLD_PIXELS
maxThreshold: 0.01,
// Maximum color delta (0...255):
maxDelta: 20,
// Maximum surrounding pixel offset
maxOffset: 0,
renderComposition: true, // Should Rembrandt render a composition image?
compositionMaskColor: Rembrandt.Color.RED // Color of unmatched pixels
})
// Run the comparison
rembrandt.compare()
.then(function (result) {
console.log('Passed:', result.passed)
console.log('Pixel Difference:', result.differences, 'Percentage Difference', result.percentageDifference, '%')
console.log('Composition image buffer:', result.compositionImage)
// Note that `compositionImage` is an Image when Rembrandt.js is run in the browser environment
})
.catch((e) => {
console.error(e)
})
```
### License
See [LICENSE.md](LICENSE.md)
### Authors and Contributors
Copyright (c) 2016 by [PhotoEditorSDK.com](https://www.photoeditorsdk.com/?utm_campaign=Projects&utm_source=Github&utm_medium=Side_Projects&utm_content=Rembrandt&utm_term=HTML5)