Trellis quantization as structured vector quantizer is able to improve
the rate-distortion performance of traditional scalar quantizers. As such,
it has found its way into the JPEG~2000 standard, and also recently as an
option in HEVC. In this paper, a trellis quantization option for JPEG XS is
considered and analyzed; JPEG~XS is a low-complexity, low-latency high-speed
"mezzanine" codec for Video over IP transmission in professional
production environments and industrial applications where high compression
rates are of lesser importance than visual lossless compression at high
speed.

A particular challenge of trellis quantization is to make it compatible with
applications where sharp rate thresholds have to be satisfied, such as in
JPEG~2000 and JPEG~XS. While the JPEG~2000 standard originally proposes a
Lagrangian "a priori" rate allocation that is based on statistical models,
such methods are less suitable for JPEG~XS which only has a very small
prefetch window of less than 30 lines available to drive its rate
allocation. In this paper, a simple trellis quantization option for JPEG~XS
is proposed that is compatible with the hard-bounds rate-allocation
requirements of this coding standard.