How it works
Sharp puts several shots of the same scene together into one picture. Everything happens in this browser tab, on your device: the photos are read from your disk, merged here, and the result is saved back to your disk. They are never sent anywhere.
Why your photos can’t leave
The page is served with a security policy that lets it talk only to sharpmerge.com, and it never sends your pictures there either: there is nothing on the server to receive them. Once the page has loaded it works with no internet connection at all — try it in flight mode.
What runs
The merging is the same engine as the Sharp app for iPhone and iPad, rewritten to run in the browser (Rust compiled to WebAssembly). It lines the frames up when asked — by comparing small windows of each frame with the middle one, and only moving a frame if that clearly makes it match better — then combines them a band of rows at a time, so even 45-megapixel photos fit in a phone’s memory.
- Focus lines up a focus bracket — shift, the slight change of size as focus moves, and a rolled wrist — then takes every part from the frame that had it sharpest, blended where neighbouring frames share it. You choose the detail size by comparing four on a crop. It keeps the frames on this device’s private storage while it works and removes them after.
- Clean averages every frame: the noise falls with the square root of the number of frames.
- Vanish finds, at every point, what most frames agree on and averages those frames; anything only a few frames saw — a passer-by, a car — is left out. It keeps the frames on this device’s private storage while it works and removes them after.
- Trails keeps the brightest (or darkest) frame at every point, whole pixels, so no colour is invented.
- Blend is exposure fusion: each part of the picture is taken from the frames that exposed it best.
- Pick scores every frame for detail and hands back the sharpest file untouched.
What you get
A full-resolution JPEG, with no watermark. When your photos are JPEGs it keeps their colour profile and which way up they go; nothing else about them — camera, place, time — is copied into the result.
Limits
Up to 12 photos at a time, all the same size — Sharp Pro for the web (US$15, once) takes as many as your computer can, and adds the retouch brush (paint the right frame back in where the merge guessed wrong), a 16-bit TIFF, the maps, every frame lined up and batches. JPEG works in every browser; HEIC photos open in Safari.
Projects
Each run is kept in this browser as a project: the result, its map and the settings, and each photo’s name, size and date — never the photos. Open one to see and download its result again, or choose the same photos to make it again. With Sharp Pro every run is kept, and a saved retouch can be carried on later. Projects stay on this device until you delete them.
RAW
Camera RAW files — Canon CR2 and CR3, Nikon NEF, Sony ARW, Fujifilm RAF, Olympus ORF, Panasonic RW2, Pentax PEF, DNG including iPhone ProRAW, and most others — are developed here, in every browser, free, by LibRaw. Every frame of a run is developed the same way: the middle frame’s white balance as shot and one brightness, so the frames match and a bracket keeps its stops. Not yet: Nikon’s “High Efficiency” NEFs and DNGs compressed with JPEG XL (an option on newer iPhones).