JPEG XS & WAVELET TECHNOLOGY
Most people think of JPEG XS as a low-latency compression codec — and it is. But there is a capability built into its wavelet architecture that goes far beyond simple compression: the ability for any receiver to independently decode a full 4K frame, an embedded HD layer, or a specific crop region, all from the same single compressed stream. This is wavelet scalability, and it changes how you think about video distribution over IP.
Why wavelets are different
Traditional video codecs — H.264, H.265, even JPEG 2000 in many configurations — compress a frame by predicting differences between frames or blocks. To decode any part of the image, a receiver typically needs the entire compressed bitstream for that frame.
JPEG XS is a wavelet-based codec. A wavelet transform decomposes an image into a hierarchy of frequency sub-bands — low-frequency components that carry the overall structure of the image, and progressively higher-frequency components that add fine detail. This hierarchy is preserved in the compressed bitstream.
The key insight: because the bitstream is structured by frequency sub-band, a receiver can choose to decode only part of it — and get a valid, complete image at a lower resolution. The low-frequency sub-bands alone reconstruct a small version of the image. Adding more sub-bands increases resolution progressively. This is called resolution scalability, and it is inherent to the wavelet architecture — not an add-on feature.
What this means in practice
In a JPEG XS stream, the wavelet decomposition means a single compressed bitstream simultaneously contains:
- An embedded half-resolution layer — HD from a 4K stream, for example
- An embedded quarter-resolution layer — and so on down the hierarchy
- The ability to crop a region— decode only a spatial sub-region of the frame without decoding the full image
- The full resolution image — 4K, 1080p, or whatever the source resolution is
Critically, these sub-images are not separate streams. They are embedded in the single compressed bitstream. A receiver that only needs HD from a 4K source can do so by partially decoding the existing stream — no re-encoding at the sender, no separate network path, no extra bandwidth.