Desktop app
The desktop app runs Dezoomify natively on Windows, macOS, and Linux, without a browser's limits. Use it when:
- the image is very large: a browser may refuse to display or save
images beyond a certain size; the desktop app assembles images of any size and writes them directly to disk;
- the site refuses visitors from other pages: the app can introduce
itself as coming from the site's own viewer page;
- you need a specific file format: the website saves PNG; the desktop
app saves PNG, JPEG, TIFF, and more, including a local zoomable copy for gigantic pictures;
- a save got interrupted: with the resume option, already-fetched
pieces are kept and the job continues where it stopped.
Install
- Go to the releases page
and save the version for your operating system.
- Unpack it and start the program.
- Depending on your system, you may need to confirm that you trust the app:
on macOS, use *System Settings → Privacy & Security → Open Anyway* the first time you start it. The app is not professionally signed because Dezoomify is a free project without a paid signing certificate.
Save an image
Paste the address of the page (or of the image description file) into the app and choose where to save the result, exactly like on the website. You can also start the app with the address as an argument, or drive it from the terminal; see the command-line guide.
Members-only sites: the desktop app cannot sign in by itself. Get the image address with the browser extension and send the job to the desktop app; the extension asks for your consent before passing the site's credentials, which stay in memory only.
Sites that refuse visitors: some servers only send their image to requests that appear to come from the site's own viewer. If the save fails with a "forbidden" style error, tell the app which page the image belongs to (most image viewers open with such a page) and it will introduce itself as coming from there. On the command line, this is the --header "Referer: …" option; see protected pages.
Choosing the file format
The format follows the file name you choose: picture.jpg saves a JPEG, picture.png a PNG, picture.iiif a local zoomable copy you can open in a browser.
- JPEG is the common choice and produces small files, but pictures are
limited to 65,535 pixels per side and the whole picture must fit in your computer's memory.
- PNG is lossless (no quality loss) and works even for gigantic
pictures: it is written to disk as it goes, without needing to hold the whole image in memory. It produces much larger files.
- A local zoomable copy (
.iiif) is best for images of hundreds of
megapixels or more: regular image viewers struggle with files that large, but a zoomable copy stays comfortable to explore.
Resuming an interrupted save
Start the app with a resume folder (--tile-cache <folder> on the command line). Every saved piece is kept there; if the save stops, run the same command again and it picks up where it left off. The folder also contains the individual pieces if you prefer to assemble them with other tools.