OVERLAY CROP GUIDE
How to Overlay Two Images Online for Comparison
Updated June 19, 2026
Placing two images side by side is useful for presentation, but a transparent overlay is better for detecting small differences in position, scale, crop, and editing. Overlay Crop lets you compare the files as independent layers before exporting them separately.
Overlay comparison versus side-by-side viewing
Side-by-side images show an overall change. A semi-transparent overlay reveals exactly where edges, facial features, objects, and background lines differ.
Use the overlay while preparing the files, then use the aligned exports in a side-by-side design, slider, or video.
Upload the reference and comparison images
Add the reference image first and the comparison image second. The comparison layer appears above the reference and can be moved, resized, hidden, or made transparent independently.
The two source files do not need to share the same resolution or aspect ratio.
Set a useful transparency level
Reduce the opacity of the upper image to about 50 percent. If both images are very bright, use a lower value; if one image is dark, increase it until both remain visible.
The correct transparency makes doubled edges and misaligned landmarks easy to identify.
Choose stable reference points
For portraits, compare pupils, nose, mouth, jawline, and shoulders. For buildings, use corners, windows, doors, floor lines, and roof lines. For products, use outer edges, logos, buttons, and packaging corners.
Adjust scale first, then position. This reduces repeated back-and-forth corrections.
Inspect editing and composition differences
Once the images are aligned, the overlay can reveal retouching, background cleanup, removed objects, body or product shape changes, brightness adjustments, and crop differences.
Hide and show the top layer to confirm whether a difference comes from the edit or from camera movement.
Crop both files consistently
Choose a final ratio and output size after alignment. The same crop frame is applied to both images while each layer keeps its own transform.
This is useful for 4:5 social posts, 9:16 vertical videos, website sliders, GIFs, and presentation slides.
Export separate comparison files privately
Overlay Crop does not permanently flatten the two layers. Each image is exported separately at the same dimensions, ready for a slider, carousel, animation, or portfolio.
The browser processes the selected images locally, which is useful for personal portraits, client material, and unpublished work.
FAQ
Can the two images have different resolutions?
Yes. Each image can be positioned and resized independently before export.
Does the tool permanently merge the images?
No. The overlay is used for comparison and alignment; the files are exported separately.
Can I compare more than two images?
Yes. Up to five layers can be added in one editing session.
Overlay image crop editor
Upload your original and edited photos, lower the top image opacity, then align facial features or fixed background points. Every exported image uses the same crop ratio and pixel dimensions.
Start cropping