Sharing huge images with Deep Zoom tiles in Paint by Zaweba

Very large images are hard to share. A panorama stitched from dozens of photos, a high resolution scan of a map or a painting, or a detailed technical drawing can run to many thousands of pixels in each direction. Sent as a single file it is slow to download and awkward to view. File > Export > Deep Zoom Tiles in Paint by Zaweba solves that by writing a DZI pyramid and a self-contained HTML viewer.

What a tile pyramid is

A Deep Zoom export cuts the image into small tiles at many levels of detail. The top level is a tiny overview; each level below doubles the resolution until the bottom level holds the full-size picture. The DZI file describes the structure.

A viewer then loads only the tiles needed for what is on screen. Zoomed out, it shows a handful of small tiles. Zoom into a corner and it fetches the detailed tiles for that corner only. The viewer never needs the whole image at once, so even an enormous picture opens almost instantly and stays smooth as you explore it.

The HTML viewer

Paint by Zaweba writes a self-contained HTML viewer with the tiles. Open it in a browser and you can pan and zoom straight away. Copy the folder to a website and the same viewer works there, with nothing else to install. That makes it easy to put a zoomable image on a site, include it in a digital exhibition, or send it to a client on a USB stick.

Good uses

Panoramas and landscapes where the joy is in finding details. Scans of artwork, where viewers want to see brush marks and texture. Old maps and plans with fine lettering. Product photography where a customer wants to inspect stitching or a finish. Microscope and astronomy images. Large group photos where everyone wants to find their own face.

Preparing the image

Finish the edit first. Retouch, adjust and sharpen at full size in Paint by Zaweba, because every flaw is easy to find once viewers can zoom in. Flatten or hide any working layers you don't want in the export.

Think about the edges. A deep zoom image invites close inspection, so check corners and borders for stitching errors or dust at full magnification before you export.

Mind the file count. A large image produces a lot of small tile files. That's normal and is what makes the viewer quick, but it means uploading the folder rather than a single file. Keep the folder structure intact when copying it to a server.

Choosing between the export options

Deep Zoom is one of several specialist exports in Paint by Zaweba. Save for Web is for single images that need to be small. Export As makes several sizes at once. Slices cut a design into named pieces with an HTML page. Deep Zoom is for the opposite case: an image too big for any of those, which deserves to be seen at full detail without asking anyone to download it all.

Because it writes plain files and an HTML page, there's no service or account involved. You make the tiles on your own PC and put them wherever you like.