Image compare (diff)
Spot differences between two images
How to use it
- Drop the original picture, then the one to check. Use the arrows if they are the wrong way round.
- Choose how to see the differences, then press Compare.
- Read the numbers and download the picture of the differences.
Questions
What counts as a change?
A pixel counts as changed when its red, green or blue value differs by more than the setting. See-through pixels are compared as they look on a white page, so two pictures that look the same are the same.
What is the similarity score?
PSNR, a standard measure of how close two pictures are, in decibels. Above 40 most people cannot see a difference. Below 30 the differences are easy to see. Identical pictures have no score.
What if the pictures are not the same size?
By default the second is stretched to the size of the first, and you are told. If the shapes differ, most pixels will count as changed, so check the sizes first. You can ask the tool to stop instead.
Why does a JPG of the same picture show changes?
JPG changes colors slightly every time it is saved. Raise "Ignore differences smaller than" to about 8 to see only real changes.
Are my pictures uploaded anywhere?
No. The file is read in your browser, on your device. It is not sent to a server.
Are my files uploaded anywhere?
No. This tool runs in your browser, so your files stay on your device and are never sent to a server.
Is it free?
Yes, you can use it for free. A subscription removes limits and unlocks premium tools.