Choose a reference
Use the more stable or authoritative image as the base photo.
Precision comparison
Blend two images in one frame
Upload both views, then move the opacity control. Doubled edges reveal where scale, position, shape, or content differs.
Upload before and after photos
What an opacity overlay can reveal
At approximately 50% opacity, matching edges remain relatively stable while differences form doubled or ghosted edges. This helps with document registration, photo restoration, retouching review, construction-plan revisions, screenshot changes, landscape progress, and repeated camera views.
An overlay shows difference, but it does not explain its cause. A doubled edge may come from a real change, camera movement, lens distortion, scaling, or a mismatched crop.
A practical inspection method
Start at 50%
An equal blend usually makes displaced edges easiest to notice.
Sweep the range
Move between 0% and 100% to identify which image contains each detail.
Save with context
Download the useful blend and explain the opacity and source images when sharing it.
Reading common overlay patterns
| Pattern | Possible explanation | Next check |
|---|---|---|
| All edges doubled equally | Whole-image position shifted | Check camera or crop alignment |
| Edges diverge near corners | Scale, perspective, or lens difference | Compare central and corner landmarks |
| Only one object ghosts | Local object or edit changed | Confirm surrounding features still align |
| Color changes but edges match | Lighting, grading, or color correction | Review exposure and white balance |
Do not treat an overlay as automatic proof. Record how the images were captured and aligned when the result will support a technical or factual claim.
Overlay questions
Which image changes opacity?
The second, overlay image changes from transparent at 0% to fully visible at 100%. The base image remains underneath.
Why does everything look blurred?
The images are not aligned or contain different detail. At partial opacity, displaced edges naturally create a ghosted appearance.
Can this calculate a numeric difference?
No. This is a visual blend, not a pixel-difference measurement or scientific registration tool.
What does Download save?
It saves the canvas at the currently selected opacity as a PNG on your device.