Highlight the Difference Between Two Images
Compare two images pixel by pixel — every change is highlighted, the rest is dimmed, and you get the exact percentage that changed.
Add two images of the same size to highlight what changed.
What a pixel difference shows
An image difference (or 'image diff') compares two pictures pixel by pixel and shows you exactly where they disagree. It's the precise counterpart to the eyeball test: instead of squinting at two thumbnails, you get a single overlay where changed pixels are painted in a bright colour and the unchanged background is dimmed to grey.
This tool also reports the percentage of the image that changed, and a threshold slider lets you ignore tiny differences from JPG compression or slight colour shifts. It's ideal for spotting edits, catching visual regressions in screenshots, verifying exports, and proofreading designs.
How to find the difference between two images
- Add both images. Drop them into slots A and B. For an exact diff they should be the same size.
- Set a threshold. Raise it to ignore compression noise, lower it to catch the faintest change.
- Find differences. Click the button — changed pixels light up and the percentage appears.
- Download the overlay. Save the highlighted difference image if you need to keep or share it.
Tune the threshold
If two JPGs of the same scene show diff noise everywhere, raise the threshold until only the real change remains. For pixel-perfect work like UI screenshots, drop the threshold to zero so even a single off pixel is flagged.
How image difference works here
Compares the two images pixel by pixel: for every pixel it measures how far the red, green, blue, and transparency values have moved, and if any channel moves past the threshold the pixel is painted rose while everything unchanged fades to dim grayscale — plus it reports the exact percentage of pixels that changed.
- Best for
- Knowing precisely which pixels differ and by how much — the exact, measurable counterpart to eyeballing two thumbnails.
- Practical tip
- Two JPGs of the same scene will light up with speckle everywhere because compression nudges almost every pixel — raise the threshold until that noise disappears and only the real change is left; for pixel-perfect work like PNG UI screenshots, drop the threshold to zero so even a single off pixel is flagged.
Real-world uses
- Catching visual regressions between two UI screenshots
- Verifying that a compressed or converted export is visually identical
- Proofreading two versions of a design or document for stray edits
- Confirming a watermark, redaction, or retouch only touched the area it should
More ways to compare images
Frequently asked questions
How do I see what changed between two images?
Load both, then click Find differences. Changed pixels are highlighted, unchanged pixels are dimmed, and the percentage that changed is shown.
Why do I see noise across the whole image?
That's usually JPG compression. Raise the threshold slider until the noise disappears and only the meaningful change is left.
Do the images need identical dimensions?
For an accurate pixel diff, yes. If they differ, the tool compares on a canvas the size of the larger image, so the extra area shows as changed.
Where are my images processed?
The comparison happens in your browser, so the results are created on your own device. How any data associated with the tool is handled is described in our privacy policy.
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