This is a 46,000 x 32,914 pixel deepzoom image of a slide from the openslide test data, using 512 x 512 JXL images for the tiles.

It seems to work well in Safari on macOS 14 and later, other browsers and platforms may need some configuring. I had to patch openseadragon to add JXL to the list of allowed tile formats, but otherwise this is all just of the box.

I generated the image pyramid with:

$ time vips dzsave CMU-1.svs x --suffix .jxl --tile-width 512 --tile-height 512
real 2m41.955s
user 21m15.100s
sys 4m37.930s

Use your mousewheel to zoom, click and drag to pan.