OpenSummary

OpenSummary turns your photos into two things you can post: a clean summary image showing the EXIF data (aperture, shutter speed, ISO, focal length, date, camera, lens), and a set of equal slices of the same photo for carousel posts.

It runs entirely in your browser. There is no server, no account and no upload: your photos are read and processed on your own device.

Live at opensummary.app.

What it does

• Summary image. Draws the photo blurred in the background with the EXIF details on top. You can adjust the blur and text size and add a copyright line.
• Split. Cuts a photo from left to right into equal slices (2 or more) so a wide shot continues across carousel slides.
• Batch. Select several photos at once. "Download all" saves every result.
• Output. JPEG files named <original>_summary.jpg and <original>_<n>of<total>.jpg.

How it is structured

There is no build step, no framework and no package manager. The whole app is static files.

index.html        The app: markup, CSS and JavaScript in one file
onboarding.html   One-time intro page, shown on first visit
exif.js           EXIF reader (fork of exif-js, see Credits)
icons/            SVG icons used on the summary image
huey.jpg          Example photos used on the onboarding page
b747.jpg

Inside index.html, the script is organised roughly in this order:

1. Setup. Loads the icons by name and defines small helpers for turning a canvas into a Blob and an image URL into an Image.
2. EXIF formatting. getExif reads the file with exif.js, a fork of exif-js. buildInfo formats the values and splits them into a top group (exposure settings and date) and a bottom group (camera, lens, copyright). Values that are missing or invalid are skipped rather than printed as NaN.
3. Drawing. drawSummary paints the blurred photo onto a canvas, then the icons and text. drawPiece crops slice i of n out of the original. All sizes are relative to the image's shorter side, so a preview and a full-resolution render look the same.
4. UI and rendering. render runs when the files or options change. It produces a small preview for the screen and defers the full-quality render until the user downloads, using the same parameters. Output is capped at 16 megapixels to stay within mobile canvas limits. Rapid slider changes are debounced, and a run counter cancels stale renders.
5. Downloads and input. "Download all" saves files one at a time. Drag and drop is supported on the upload box.

Three small pieces of state are kept in localStorage: whether the onboarding page has been seen, the theme choice, and the last copyright text you typed (so it is autofilled next time). Nothing else is stored. Crawlers skip the onboarding redirect.

The only external request the app makes is for context-filter-polyfill, loaded from jsDelivr. It makes the canvas filter property (used for the blur) work on iOS, where it is not supported natively. Fonts and styles for the app itself are local.

Running it locally

Any static file server works. For example:

git clone https://github.com/LetsPlaySimi/OpenSummary.git
cd OpenSummary
python3 -m http.server 8000

Then open http://localhost:8000. Opening index.html directly from disk mostly works too, but a local server is more reliable.

Deployment

The site is deployed at opensummary.app as plain static files. To host your own copy, upload the contents of the repository to any static host. No configuration is needed.

Contributing

Issues and pull requests are welcome. Keep changes small and focused where you can, and test with a few real photos, including ones with missing EXIF data.

Vibecoding is 100% allowed. Code written with an AI assistant is welcome here, and you do not need to disclose it. The only standard is that the change works and you have run it yourself.

By contributing, you agree that your contribution is released under the same license as the project (see below).

Credits

OpenSummary builds on two open source libraries:

• exif-js reads the EXIF data from photos in the browser. OpenSummary uses a fork with fixes, which is included in this repository as exif.js.
• context-filter-polyfill by David Enke makes ctx.filter (the canvas blur) work on iOS.

Thanks to their authors and contributors.

License

OpenSummary is licensed under Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International (CC BY-NC-SA 4.0). In plain terms:

• You can copy, modify and share it.
• You must credit OpenSummary and link to this repository.
• Anything you build from it must be released under the same license.
• You may not use it for commercial purposes or make money from it in any way.

The full text is in LICENSE. The libraries listed under Credits are not covered by this license and keep their own.