Find what moved
between two images
Drop in two photos of the same scene. Drift measures how far one shifted, lines them up, and paints every real difference in red.
Nothing is uploaded. The images never leave this tab.
A
First imageClick, drop or paste
B
Second imageClick, drop or paste
No images handy? Try one of the examples →
Horizontal—
Vertical—
Rotation—
Scale—
Changed—
Match—
Lining the images up…
How it works
1 · Measure the shift
Both images go through a Fourier transform. Dividing out the magnitude leaves only phase, and the inverse transform of that is a single sharp spike sitting exactly at the offset between them. It is called phase correlation, and because the magnitude is thrown away it is unbothered by one photo being brighter than the other.
2 · Line them up
The second image is resampled by the measured offset. Turn on rotation and scale and a second pass runs first, on a log-polar resampling of the spectrum, where a turn becomes a sideways shift and a zoom becomes a vertical one.
3 · Mark the difference
What remains after alignment is real change. Pixels that differ by more than the sensitivity threshold are painted red, with a majority filter removing the speckle that noise and resampling leave behind.