Compare two images and find the differences
Compare two images pixel by pixel and mark the differences in red
Your files stay with you. Conversion happens inside the browser; no file is ever uploaded to a server.
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How it works
Tap or click the box and choose two images; the one you pick first counts as the first image. Exactly two files are needed, so remove any extra ones with ×. Press "Compare" and the two images are checked pixel by pixel; you get a PNG with every changed pixel in red. The result line says how many pixels differ, what percentage that is, and the x-y range where the changes sit. Example: give it a screenshot of a web page before and after an update and only the changed button turns red, with a line such as "0.8% different, between x 120–310, y 40–88". If the second image has a different size, it is scaled to the first. Everything runs in your browser; the images are not uploaded.
This tool is also known as compare images, compare two images, image difference, find difference between two images, image diff online, photo comparison.
What is Pixel difference?
Pixel difference is how far apart two images are in colour at the same position. This tool compares pixels with the YIQ colour measure, which is close to how the eye works: it weighs a change in brightness more than a change in hue. When the difference passes the chosen sensitivity threshold, the pixel counts as different and is painted red.
What is Sensitivity threshold?
The sensitivity threshold sets how small a difference still counts. JPG shifts colours slightly every time it is saved, so at high sensitivity even two JPG copies of the same photo show scattered differences. Medium suits most jobs; choose low to see only real content changes, and high to catch a single shifted pixel in screenshot tests.
Comparing images vs. comparing text: what is the difference?
A text comparison matches lines and words of two documents, tells you what was added or removed and copes with things moving around. An image comparison measures pixels at the same position: if a line of text moves down by one row, every pixel under it counts as different. If you know the change is in the wording, compare the text; if you are checking layout, colour or appearance, compare the images.
No alignment: a shifted photo turns almost entirely red
Pixels are compared at the same position. If two photos were taken by hand, if one moved by a few pixels, was rotated or cropped differently, nearly every pixel counts as different and the result is mostly red. The tool does not answer whether two photos look alike; it compares two versions of the same frame.
The best inputs come from the same source: two screenshots of a page, two versions of a design, a compressed and an original copy of one file. For spot-the-difference puzzles it works when the two pictures are the same size; crop the puzzle into two separate files first.
How to read the result line
The percentage is the share of changed pixels in the whole image. 0% means the images are identical at the chosen sensitivity. Values under 0.1% are usually compression noise or anti-aliasing; if they vanish one sensitivity step lower, they are not a real change.
The coordinates are the top-left and bottom-right corners of the box around all differences, in pixels from the left (x) and from the top (y). When the changes sit in one place the box is small and points straight at the changed element. Very large images are compared with the long side reduced to 4096 pixels, and the coordinates use that size.
Frequently asked questions
How do I find the difference between two images?
Choose the two images in the box on this page and press "Compare". Changed pixels are marked in red, and the result line shows what percentage of the image changed and where.
Can I compare images of different sizes?
Yes. The second image is scaled to the size of the first before the comparison, and the result line mentions it. If the aspect ratios differ, the second image is stretched, which adds to the differences.
Why does the same photo show differences?
Usually one copy was saved again as JPG and its colours shifted slightly, or one photo moved by a few pixels. Set sensitivity to "Low"; a shift will not disappear because the tool does not align images.
Are my images uploaded?
No. The comparison runs inside your browser and the images never leave your device.