Getting the Full Picture Out of Zoomable Image Viewers

You've found a high-resolution map, painting, or archival photograph on a museum or library website, and it's beautiful. The only problem is that the site only lets you pan and zoom around it in a viewer, and there's no download button in sight. Dezoomify is a project that goes and finds the full image behind that viewer, assembles the tiles into a single picture, and lets you save it.

What It Does

Dezoomify works with the zoomable image viewers used by museums, libraries, archives, and map collections. These viewers typically load an image in tiles at different zoom levels rather than serving one big file. Dezoomify figures out the underlying image and stitches those tiles back together into something you can keep.

The interesting part is the architecture: the same codebase runs across four platforms, each with different capabilities. There's a website (nothing to install, but the least powerful), a browser extension for Chrome and Firefox, a desktop app for Windows, macOS, and Linux, and a command-line tool for scripting. On the format side, it supports IIIF, Deep Zoom, Zoomify, Google Arts & Culture, krpano, and other image formats. If you already know the address of the image's description file (an info.json, ImageProperties.xml, or .dzi file), you can paste that directly instead of the viewer page.

Why It's Cool

• The platform tiers are honest about tradeoffs. The README doesn't pretend every version is equal. The website is easiest to run but some sites block it, it can't use your browser login, and the browser caps the maximum image size. The extension works around some of those restrictions and handles signed-in pages, but keeps the same size limits. The desktop app saves larger images, opens local files, and supports PNG, JPEG, TIFF, ZIF, WebP, and IIIF tile folders. That kind of clarity saves you from downloading the wrong thing and wondering why it failed.

• Resumable saves on desktop. Interrupted saves can resume using cached tiles. If you've ever pulled down a huge tiled image over a flaky connection, you know why this matters. Image size is limited by your available memory rather than an arbitrary cap.

• The CLI is built for bulk work. The command-line tool has the same saving capabilities as the desktop app, but adds the ability to choose a particular image or zoom level, limit the resolution, or save a list of addresses with --bulk. A Linux x86_64 executable ships in the dezoomify-cli archive on the releases page.

• It tells you what to do when things go wrong. The README has a dedicated troubleshooting section: no image found, login required, image too large or blank. Each one points you at the right tool rather than leaving you stuck.

How to Try It

The fastest path is the website:

1. Open the page that shows the zoomable image and copy its address.
2. Paste it into the Dezoomify website and press Dezoomify.
3. When the image is ready, press Save to keep the PNG file.

If that doesn't work, move up the ladder. Install the browser extension for Chrome or for Firefox, open the image's page, and click the Dezoomify button in your toolbar. For signed-in pages, the extension is the one that can reuse your session.

For large images, grab the desktop app. Installers come as .msi for Windows x86_64, .dmg for Apple silicon Macs, and .deb for Linux x86_64. They're unsigned, so your OS may ask you to confirm you trust the installer; after that, use Help → Check for updates… to install a signed update.

If you want to script it, the CLI lives in the same releases page. To build it from source, check the repository:

https://github.com/lovasoa/dezoomify

Final Thoughts

Dezoomify solves a narrow but genuinely annoying problem, and it does so with a sensible spread of options rather than one tool trying to be everything. The honest framing about what each platform can and can't do is refreshing. It's best suited to researchers, archivists, map enthusiasts, and anyone who regularly needs to pull high-resolution images out of institutional viewers. The caveat is real, though: no app works with every website, and the README says so plainly. If the website fails, the extension or desktop app is your next stop. Start with the site, escalate as needed.

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