FreeImage Compare
Compare two images and find the differences
Changed pixels highlighted, a heat map, the share that differs and the PSNR.
Drop an image here, or .
Runs in your browser. Nothing is uploaded.
Image Compare: how to use it
- Choose the two images together: the original first, then the other version.
- Pick how to show the differences and set the threshold.
- Read the share of changed pixels and download the result.
Tips
- Raise the threshold to hide JPEG noise and show only real edits.
- Use the heat map to see how strong each change is, not just where it is.
Image Compare: what it does and when to use it
Image Compare shows what changed between two versions of an image: the pixels that differ are marked in red over a faded copy, with a box around the changed area, or shown as a heat map of how much each pixel changed. You also get the share of pixels that differ, the largest difference and the PSNR, a standard measure of how close two images are.
It is useful for spotting an edit someone made to a photo or a document, checking a website screenshot before and after a code change, comparing two exports from a design app, or seeing how much a compressed copy lost. Ignore differences under hides the tiny changes that JPEG compression makes, so only real edits show. Side by side and a 50% overlay are there for a visual check.
Choose both images at once; the first is treated as the original. If they are different sizes, the second is scaled to match before comparing, and the result says so. Both images stay on your device. To see how much a re-save costs in quality and size, compress a copy with the Image Compressor and compare it with the original here.
Image Compare: frequently asked questions
How do I find the difference between two images?
Choose both images at once. Changed pixels are shown in red over a faded copy of the original, with a box around the changed area, and the tool tells you what share of the pixels differ. Related guide: Colour-blind friendly charts, maps and designs.
Why does it show differences in an image that looks the same?
Re-saving a JPEG or WebP changes many pixels slightly. Raise Ignore differences under to 10 to 20% so only visible changes are marked, or look at the PSNR: above about 40 dB the eye cannot see a difference.
Can it compare images of different sizes?
Yes. The second image is scaled to the size of the first before comparing, and the result says so. For the most precise comparison, compare images of the same size. Related tool: Image Compressor.
What is PSNR?
Peak signal-to-noise ratio, a standard measure of how close two images are, in decibels. Higher is closer; identical images have no noise at all, so their PSNR is infinite.