Use it at stereo.cbbldtgthr.dev
A small static web app for parallel (defocus) free-viewing of a stereo pair: two photos side by side, one for each eye. Pick left and right images (or use bundled examples), then relax your eyes so each image goes to the correct eye.
Install for offline use
The hosted app is a Progressive Web App. Open stereo.cbbldtgthr.dev once while online so the service worker can cache the shell and bundled examples. Then use your browser’s Install (desktop) or Add to Home Screen (mobile) option—often in the address bar menu or share sheet. After that you can launch it with no network; your own photos still need to be chosen from the device when offline.
What makes it different
Scroll-wheel zoom does not resize the whole page. Each eye’s image lives in its own clipped frame; zoom and pan stay locked together so the same point in the scene stays aligned in both frames. That avoids the usual problem where browser zoom or a single “fit width” control throws off spacing for free-viewing. Many stereo tools resize the pair as one unit or only offer a coarse size control—here, zoom is interactive and centered under the cursor (or the frame center from the keyboard).
Controls
- Scroll — zoom both panels in sync (cursor anchor).
- Drag — pan both images together inside their frames.
- ← / → — relative size (how much of the viewport the pair uses).
- Up / down arrows — zoom toward the center.
- Gap, crop — spacing between frames and horizontal crop (percentage), still side by side.
Run locally
Open index.html in a browser, or serve the folder with any static file server (paths are relative).
Docker
docker compose up -d --build
Then open http://localhost:8083 (see docker-compose.yml for the host port).
Image is nginx:alpine; compose caps memory at 32 MB for a tiny footprint.