How to use Image Comparison Tool
- Choose exactly two JPEG, PNG or WebP images. Use Up and Down to set which goes first.
- Set a channel difference threshold from 0 to 255. Zero flags any changed channel value.
- Select Compare images and read the changed-pixel count.
- Download image-comparison.png to keep the two images and the red difference panel together.
Example: Image Comparison Tool
A local worked example using the inputs and settings below for image comparison tool.
Options
- File order
- The first and second images are compared under the stated dimensions policy. Check that they represent the same crop before interpreting differences.
- Threshold
- The threshold suppresses differences below the selected pixel criterion. A quiet difference view does not prove byte identity or visual equivalence at every scale.
Supported inputs and limits
Where your input is processed
This tool processes your input in this browser. Your text and files are not uploaded to UseFreeTools. Check this tool's limits for anything it may save on your device.
Reading the third panel
The first two panels show the inputs in order. Red positions in the third panel crossed your threshold; dark positions did not. The count uses the full size of the larger image, so areas outside the smaller image can count when they differ from transparency.
Questions about Image Comparison Tool
Why does a shifted photo show many differences?
The page aligns top-left pixels directly. It does not straighten, scale or find matching features, so even a one-pixel shift can change many positions.
Does transparency count?
Yes. Red, green, blue and alpha are compared before the white display background is drawn.
What does a threshold of 10 mean?
A pixel is marked if at least one channel differs by more than 10 on the 0–255 channel scale.