Camera Overlay App to Compare Photos: Build Your Own (2026)

If you’re searching for an app that overlays a photo on top of your camera to compare proportions or track changes, you’ve probably noticed most options are either bloated, generic, or built for a totally different use case than yours. Here’s how to just build the exact tool you need.

Is there an app that overlays two photos? Yes — but “generic” is the problem

There are camera overlay apps for before-and-after comparisons, and some real-time before-and-after comparison apps do let you overlay an image on a live camera feed. If you’re comparing weight-loss photos, renovation progress, or plant growth, one of those might technically work. But the moment your need gets specific — comparing a sketch against a reference photo to check proportions, say — you’re stuck fighting sliders and settings meant for someone else’s use case.

The faster fix in 2026 is to build your own version in Auto. You describe what you’re comparing, snap or upload your images, and Auto builds a small personal app — a Frame — shaped around exactly that task. No app store listing, no unused features, no ads. Just the overlay tool you actually need.

Building a proportion-comparison overlay in Auto

Here’s the basic path:

Describe the comparison you want to make. Be specific — “compare my sketches against photo references so I can check proportions” gives Auto much more to work with than “photo overlay app.”
Ask for a storage area for your images. If you’ll be comparing dozens of sketches over time, tell Auto you want an uploaded-image library, not just a one-off upload box.
Ask for selection and overlay controls. Specify that you want to pick a reference image and a sketch, layer them in a canvas view, and choose which one is “active.”
Ask for gesture controls. Two-finger scroll to move, pinch to scale — this is what makes the overlay actually useful instead of just decorative.
Let Auto fix its own bugs. Sometimes the first build throws errors. You don’t need to understand them — just paste them back and ask Auto to fix it.

The whole process takes minutes, and what you get fits your workflow instead of the other way around.

How someone built theirs

One Auto user wanted to check their figure-drawing proportions against reference photos. They asked for a Frame that would let them upload and store reference images and sketches, pick one of each, and overlay them on a canvas — with the ability to select whichever image was active and move or resize it using two-finger scroll and pinch gestures.

The first build had some TypeScript errors around touch-event handling and a selection component. They pasted the build error log straight back into the chat, and Auto fixed the code without them needing to touch a line of it. The result — nicknamed “Sketch Compare” by its builder — is a working proof that this kind of tool doesn’t need to be a polished app store product to be genuinely useful.

FAQ

Is there an app that overlays two photos for general use, not just sketches? Yes, but general-purpose overlay apps compromise on controls. Building your own in Auto lets you set the exact gestures and image sources you need.

Can I use this as a real-time before-and-after comparison app? You can ask Auto to build toward live camera overlay instead of static images if that’s your use case — just describe it clearly upfront.

Do I need design or coding skills to build this? No. You describe the Frame in plain language, and if something breaks, you can paste the error back and Auto resolves it.

Can I keep changing it later? Yes — since it’s your own Frame, you can ask for new features anytime, like tagging images or adding opacity controls.