Resemble.js

Analyse and compare images with Javascript and HTML5. More info & Resemble.js Demo. If you need NodeJS support, take a look at node-resemble or node-resemble-v2.

Get it

npm install resemblejs

bower install resemblejs

Example

Retrieve basic analysis on an image:

var api = resemble(fileData).onComplete(function(data){
	console.log(data);
	/*
	{
	  red: 255,
	  green: 255,
	  blue: 255,
	  brightness: 255
	}
	*/
});

Use resemble to compare two images:

var diff = resemble(file).compareTo(file2).ignoreColors().onComplete(function(data){
	console.log(data);
	/*
	{
	  misMatchPercentage : 100, // %
	  isSameDimensions: true, // or false
	  dimensionDifference: { width: 0, height: -1 }, // defined if dimensions are not the same
	  getImageDataUrl: function(){}
	}
	*/
});

Scale second image to dimensions of the first one:

//diff.useOriginalSize();
diff.scaleToSameSize();

You can also change the comparison method after the first analysis:

// diff.ignoreNothing();
// diff.ignoreColors();
diff.ignoreAntialiasing();

And change the output display style:

resemble.outputSettings({
  errorColor: {
    red: 255,
    green: 0,
    blue: 255
  },
  errorType: 'movement',
  transparency: 0.3,
  largeImageThreshold: 1200,
  useCrossOrigin: false
});
// resembleControl.repaint();

It is possible to narrow down the area of comparison, by specifying bounding box:

resemble.outputSettings({
  boundingBox: {
    x1: 100,  // left
    y1: 200,  // top
    x2: 200,  // right
    y2: 600,  // bottom
  }
});
// resembleControl.repaint();

By default, the comparison algorithm skips pixels when the image width or height is larger than 1200 pixels. This is there to mitigate performance issues.

You can modify this behaviour by setting the largeImageThreshold option to a different value. Set it to 0 to switch it off completely.

useCrossOrigin is true by default, you might need to set it to false if you're using Data URIs.

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Created by James Cryer and the Huddle development team.