What is this?
A JPIP (ISO/IEC 15444-9) foveated-decode demo. Three concentric view-window requests
are sent per mouse move: a small sharp fovea around the cursor, a medium-resolution
parafovea, and a coarse full-image periphery. The server streams only the
precincts each region needs; the client reassembles them and decodes the composite
JPEG 2000 / HTJ2K codestream in WebAssembly. Bandwidth per frame is a small fraction
of a full-image decode.
How to operate
- Click Connect (the server URL is already filled in).
- Move the mouse over the image — the sharp fovea follows the cursor.
- Adjust Reduce, Parafovea ratio, Periphery ratio to trade
detail for bandwidth.
- The stats line below the image reports fetched bytes, decode time and FPS.
Related: pan-and-zoom viewer for
gigapixel images.