How to Create a Diff of Two Images

By  on  

When I was a child, I loved looking for Waldo in the "Where's Waldo?" book series. These days I'm a sucker for TMZ's "What's the Big Frigin Difference" images, where TMZ slightly changes an image and you have to spot the differences between the two. That got me to thinking -- how easily could I automate diff'ing two images? This StackOverflow post was gold.

To create a diff of two similar images, we'll use ImageMagick's convert command line utility with a large host of configurations:

convert '(' image1.png -flatten -grayscale Rec709Luminance ')' \
        '(' image2.png -flatten -grayscale Rec709Luminance ')' \
        '(' -clone 0-1 -compose darken -composite ')' \
        -channel RGB -combine diff.png

How effective is this command with its configuration arguments? Let's have a look:

Original Image

Modified Image

Diff'ed Image

The diff image result is pretty informative! The size of the sunglasses is clearly presented, and if you look closely, you can see one skull at the top-right of the shirt has been flipped.

Whatever your reason for wanting to identify the difference two images, ImageMagick's convert tool is impressive. You can do a million things with ImageMagick; check out my Media tutorials to learn more awesome ways to modify images, videos, and audio!

Recent Features

  • By
    LightFace:  Facebook Lightbox for MooTools

    One of the web components I've always loved has been Facebook's modal dialog.  This "lightbox" isn't like others:  no dark overlay, no obnoxious animating to size, and it doesn't try to do "too much."  With Facebook's dialog in mind, I've created LightFace:  a Facebook lightbox...

  • By
    Responsive Images: The Ultimate Guide

    Chances are that any Web designers using our Ghostlab browser testing app, which allows seamless testing across all devices simultaneously, will have worked with responsive design in some shape or form. And as today's websites and devices become ever more varied, a plethora of responsive images...

Incredible Demos

  • By
    dwClickable:  Entire Block Clickable Using MooTools 1.2

    I recently received an email from a reader who was really impressed with Block Clickable, a jQuery script that took the link within a list item and made the entire list item clickable. I thought it was a neat script so I...

  • By
    jQuery topLink Plugin

    Last week I released a snippet of code for MooTools that allowed you to fade in and out a "to the top" link on any page. Here's how to implement that functionality using jQuery. The XHTML A simple link. The CSS A little CSS for position and style. The jQuery...

Discussion

    Wrap your code in <pre class="{language}"></pre> tags, link to a GitHub gist, JSFiddle fiddle, or CodePen pen to embed!