How to Overlay a Sketch on a Photo to Check Proportions (2026)

If you’re trying to figure out how to overlay a sketch on a photo to check proportions, you’ve probably already looked for a photo overlay app for artists and found a pile of generic options that almost fit — wrong aspect ratio, clunky gesture controls, or bloated with features you don’t need. There’s a faster path: build the exact tool you want yourself, in a few minutes, with Auto.

Why building your own beats hunting for one

Most “overlay drawing on reference image” tools are built for a general audience — photographers, meme-makers, whoever. They’re not built for the specific way you compare a sketch to a reference: maybe you always work from a phone photo, maybe you need to flip between multiple attempts, maybe you just want quick pinch-to-scale controls without hunting through menus. When you build your own app for this in Auto, you’re not compromising. You describe what you need, snap or upload the images, and Auto builds a mini-app — called a Frame — around your actual workflow. It’s yours: no ads, no unrelated features, no settling.

How to build it in Auto

Open Auto and describe the tool. Tell it plainly what you want: a way to compare your sketches against their photo reference so you can check proportions.
Ask for storage. Have it keep a library of every image you upload, so you’re not re-uploading the same references every time.
Set up the comparison view. Ask for a way to pick one reference image and one sketch, then overlay them in a canvas view.
Add the controls that matter to you. This is the personalization part — ask for the ability to select which image is “active” and move or scale it with simple gestures, like two-finger scroll and pinch-to-zoom, so lining up proportions feels natural.
Test it and refine. Try overlaying a real sketch and reference. If something’s off — a gesture that doesn’t register, a layout that feels cramped — just tell Auto what’s wrong. It rebuilds instantly.

This whole approach means you never have to compare sketch to reference photo using two separate apps and your own memory of where the eyes lined up. It’s one Frame, built for exactly that job.

How someone built theirs

One Auto user started with a simple, direct ask: a Frame to compare sketches against their photo reference for checking proportions, with a storage area for all uploaded images, the ability to pick a reference and a sketch, overlay them in a canvas, and move/scale the active image using two-finger scroll and pinch gestures. That one prompt captured the whole workflow.

Along the way, the build hit a real snag — a batch of TypeScript errors around touch event types and a selection component mismatch. Rather than starting over, they simply reported the errors back to Auto, which diagnosed and fixed the underlying type issues in the compare screen and image list. The Frame that came out of it, since shared as “Sketch Compare,” is proof this isn’t hypothetical — people are genuinely building these for their own sketching practice.

FAQ

Do I need to know how to code to build this? No. You describe what you want in plain language, and Auto builds and fixes the app for you — including resolving technical errors if they come up.

Can I compare more than one sketch at a time? Yes — since you’re building your own Frame, you can ask for a gallery view or side-by-side comparisons across multiple attempts, not just one pair at a time.

Is this different from a generic overlay app? Yes. A generic overlay app for artists is built for everyone; your Frame is built for your process, your gestures, and your image library.

What if I want to tweak it later? Just tell Auto what to change. It’s your app, so it can evolve as your workflow does.