Compare Images

What this tool does

Upload two images and compare them with four methods: slider, side by side, overlay and difference. Useful for checking before and after editing or compression.

Steps

1. Upload two images at once or one at a time (the first is A, the second is B).
2. Choose the comparison method.
3. For slider and overlay, press and drag on the picture or use the "Divider position" slider ("B opacity" in overlay). For difference, adjust the "Difference boost".
4. You can swap A and B or replace just one of them with another image.
5. Save the current view as PNG or send it to the workbench.

Settings

• Slider: A is on the left of the divider and B on the right. The divider has a handle, and A, B tags appear when there is enough room.
• Side by side: A on the left and B on the right at the same size.
• Overlay: lays B over A at the chosen opacity.
• Difference: compares pixels at the same position and shows black if the same and red if different. A higher boost makes small differences brighter. The share of pixels whose color differs by more than 8 is shown below.

How it works

The size of A is the base size, and B is drawn centered inside it keeping its ratio (leftover is transparent). Both images are placed on a canvas of the same size and combined by the chosen method. For difference, the largest of the red, green and blue channel differences is taken as the pixel's difference and multiplied by the boost to give the brightness.

Good to know

• If the two images differ in size or ratio, B is scaled to fit A, so the difference result is affected too. For an exact comparison use images of the same size.
• The saved image is exactly the comparison as it looks now. Side by side gives an image twice as wide.
• Results are gone when you close the tab.