Image Pixel Diff — Free Online Tool
Upload two images of the same dimensions and see exactly how many pixels differ. The diff output highlights changed pixels in red. Adjustable threshold controls sensitivity to subtle color differences. Uses the pixelmatch library for fast, accurate pixel-level comparison.
100% client-side. No uploads. Your data never leaves your browser.
How to use Image Pixel Diff
- Upload Image A (original) and Image B (modified).
- Adjust the threshold slider for sensitivity.
- Click Compare to compute the pixel diff.
- Download the diff image showing all changed pixels.
Frequently Asked Questions
What does the threshold control?
Threshold controls how different two pixels must be to count as changed. 0.0 = any difference; 0.1 = small differences ignored; 0.5 = only large differences.
Do the images need to be the same size?
Yes. The images must have identical dimensions for pixel comparison. Use Image Resizer to resize if needed.
What is the diff image?
A PNG where changed pixels are highlighted in red. Unchanged pixels are shown dimmed. Anti-aliased edges are excluded to reduce false positives.
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