Image Diff: Compare Two Images Pixel by Pixel

It compares the two images one pixel at a time. For each pixel it measures the largest change across the red, green and blue channels, and if that change is bigger than the tolerance you set, the pixel is marked as changed. The original is shown faded and every changed pixel is painted bright magenta on top, so edits are easy to spot at a glance.

The changed image is scaled to match the original's width and height before the comparison, so the diff always lines up pixel for pixel. A small note tells you when a resize happened. For the most accurate results, compare images that are already the same dimensions.

Tolerance is how different a pixel has to be before it counts as changed, from 0 to 60 per color channel. At 0 even a single-level difference is flagged, which is great for exact comparisons. Raising it ignores small differences like JPEG compression noise or anti-aliasing, so you see only the meaningful changes. It re-runs instantly on the loaded images with no re-upload.

Difference overlays the changed pixels in magenta over a faded original, the headline view. Side by side shows both images next to each other. Slider gives you a draggable before and after divider you can swipe across the image. Onion skin cross-fades the two images with a single opacity slider, which is ideal for catching small shifts in position.

No. Both images are decoded and compared entirely in your browser using a canvas. Nothing is uploaded or stored on a server, so it is safe for private screenshots, designs and photos. You can download the difference image, which is also generated locally.