About LumiRaw
LumiRaw develops raw photos in a browser tab. You drop in the file your camera saved, it makes the decisions a raw developer makes (exposure, white balance, contrast, noise, lens corrections), and you download a finished JPEG, PNG or TIFF.
The developing happens on your own computer. The program is written in Rust and compiled to WebAssembly, which the page downloads once like any other script. Your photos are read from your disk by that code and are never sent anywhere.
Why
A raw file holds far more than the JPEG the camera makes from it, but getting at it usually means installing a big program and learning it, or uploading your pictures to someone else's server. I wanted something in between: open the file, get a picture that looks like what you saw, and be able to change any decision you disagree with.
What it does with a photo
The steps run in order. Most of them start from an automatic setting measured on that photo, which you can leave alone or change:
- Framing. Straightens a tilted horizon and converging verticals if it finds them, and crops.
- Focus. Only shown when a photo measures soft. It can take back some of the blur, not all of it.
- Brightness. Exposure metered on the whole frame or on an area you mark, plus shadows, midtones and highlights.
- White balance. Automatic, or taken from something you click on that should be neutral grey.
- Colour and detail. Vibrance, clarity and noise reduction, set from the noise measured in the file.
- Local. Graduated and radial filters, and a tool for removing dust spots.
- Before and after. A slider over the result, with every automatic correction listed and each one can be switched off.
- Grade. Tone curves, looks, a colour mixer, 3D LUTs in .cube format, grain and vignetting.
- Download. JPEG, PNG (8 or 16-bit), TIFF or WebP, at full size or smaller. Several photos can be exported together as a zip.
There is also a page for merging bracketed exposures into a single raw frame with more dynamic range, before you develop it.
Lens corrections (vignetting, distortion and chromatic aberration) come from the lensfun database, which has calibrations for 1,294 lenses. They're applied when the lens recorded in the file is in it.
Your files
- Nothing is uploaded. You can check this in your browser's developer tools: the network tab shows the page, its scripts, the processing engine and the lens database, and nothing else.
- Nothing is stored either. There's no account and no analytics. Close the tab and the photo and your edit are gone.
- After the first visit it works offline, and it can be installed as an app. Once installed, it shows up under "Open with" for raw files.
- Exported files keep the camera's metadata: when the photo was taken, the camera, lens and exposure, and the GPS position if the camera recorded one. Worth remembering before you post a photo taken at home.
What it doesn't do yet
- Edits aren't saved. Reloading the page loses them.
- Everything runs on a single processor core, so a full-size export of a 26 MP file takes about ten seconds, and the 100 % view about fifteen.
- There's no brush for local adjustments, only graduated and radial filters.
- Fujifilm X-Trans files and iPhone ProRAW are supported, but have only been tested on synthetic data, not on real photos.