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Compare two images

Compare two images pixel by pixel: exact match or a per-channel tolerance, the changed-pixel count and percentage, and a difference image that highlights every disagreement in red.

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Files (2–2)
Two images of the same size (JPEG, PNG or WebP). The first is the reference, the second is checked against it.

Options

Tolerance (per channel) 0–255 How much a colour channel may differ before the pixel counts as changed. 0 insists on identical pixels; 10 forgives small encoding noise.
Questions people ask
What counts as a changed pixel?
A pixel is changed when any compared channel differs by more than the tolerance. At tolerance 0 that means a difference of a single unit is a change; at 10, small encoding noise is forgiven but a real edit still shows. Pixels are counted, not fuzzily weighted.
My images are the same picture but different sizes.
Refused with both sizes named. Resampling one to match the other would invent pixels, and an invented comparison lies. Give the two files the same dimensions and the comparison is honest.
One file has transparency and the other does not.
Both images are read into a common RGBA space by default, so alpha is part of the truth; the mode conversions are reported. If the transparency story is not what you are testing, switch to "ignore alpha" and only colours are compared.
What does the difference image show?
The reference on a dimmed background with every changed pixel highlighted in red, so you can see where the files disagree before reading the numbers. It downloads as a PNG.
Does this tell me the images "look the same"?
No, and it does not pretend to. Pixel identity and perceptual similarity are different questions; this tool answers the first with arithmetic you can check, and says so in the result.
What happens to my files?
The uploads are removed as soon as processing finishes; the difference image stays downloadable for about 10 minutes, then it is deleted automatically.