Image Diff Checker
Compare two images and highlight differences securely in your browser. Your images are never uploaded to a server—100% private visual comparison.
Compare two images pixel by pixel with SolveBar's Image Diff Checker. Differences are highlighted in red on a difference map, with a similarity score showing how much has changed. Ideal for UI regression testing, design change review, and visual QA.
How pixel-level image comparison works
The tool compares images pixel by pixel using the Canvas API's getImageData(). For each pixel position, it calculates the color difference between the two images. Pixels above a threshold difference are highlighted in the diff output.
Use cases for image diffing
UI regression testing: comparing screenshots before and after a code change. Design review: showing clients exactly what changed between two design versions. Print production: verifying that a file has been modified only where intended. Document comparison: spotting changes between two scanned document versions.
Limitations of pixel comparison
Pixel comparison is sensitive to rendering differences — the same page rendered in different browsers may show false positives due to anti-aliasing. Images must be the same dimensions for meaningful comparison.
Frequently Asked Questions
Do the two images need to be the same size?
They should be the same dimensions for meaningful comparison. Images of different sizes will be compared within the smaller image's bounds.
What does the similarity score mean?
100% means the images are pixel-identical. 99% means 1% of pixels differ. For UI screenshots, 95%+ similarity usually indicates only minor differences.
Can I compare PNG and JPG files against each other?
Yes. Note that JPEG compression adds artifacts, so comparing a JPEG against a PNG version of the same image will show compression artifacts as differences.