Compare Images – Free, No Upload

How to compare two images

Add two pictures
Drop both above or choose them. A JPG, PNG or WebP works.
Look at the difference
The slider opens first. Switch to Side by side or Difference, and move the tolerance to ignore tiny changes.
Save the difference
Save the marked difference as a PNG if you want to keep it.

What stays and what doesn't

This tool only reads. Neither file is changed.

When it won't run

Two things stop a run before it writes anything, and each is said on the file's row. A file that cannot be read is reported as damaged, and a picture too large for this device says so, with the limit. In both cases nothing is changed and your original stays as it was. A file in a format the page does not take, such as a GIF, gets a sentence instead of a row.

Comparing two pictures: what to expect

Each pair of pixels gets a distance, measured the way people see colour, with more weight on brightness than on hue. A pixel counts as different when its distance is above the tolerance. The tolerance starts low, which skips the tiniest changes. Move it all the way down to see every change at all, or up to see only the large ones.

A change in transparency counts too, even when the colour is the same. If the two pictures are different sizes, the larger one sets the size of the comparison and the smaller one is fitted inside it, so the empty edges show as differences. The page says so when it happens. A picture turned by its camera tag is compared the way it looks.

Very large pairs are compared at a reduced size to keep your device's memory in check, and the page says so. An animation is compared by its first frame, and a picture with more than eight bits per channel at eight.

Questions

Are my pictures uploaded?

No. Your pictures are processed inside your browser, on your own phone or computer, and saved straight from this page. The reading at the top of the page counts every byte sent, and it stays at 0 B.

Are the pictures sent anywhere?

No. They are read on your device, and nothing is uploaded.

How is a difference measured?

Each pair of pixels is compared in a colour space that follows how we see brightness and colour, and given a distance. Pixels over your tolerance are marked.

Why do two pictures that look the same show differences?

Saving a JPG or WebP again changes pixels a little. Raise the tolerance to ignore changes you cannot see. A tolerance of zero shows every change.

Can I compare pictures of different sizes?

Yes. The larger one sets the size of the comparison, and the smaller one is fitted inside it. Everything outside the smaller picture counts as different.

Does it change my files?

No. It only reads them.

Other things to do with a picture

All tools

Compare images, without the upload.