We propose a method to improve the performance of the recently introduced rational dither modulation (RDM) watermarking scheme. The improvement is obtained by modifying the essentially scalar nature of RDM with the introduction of a vector quantiser. The vector quantiser is based on a properly modified version of classical trellis coded quantisation, thus leading to the new trellis-coded RDM sc...

Although widely studied for many years, colour quantisation remains a practical problem in image processing. Unlike previous works where the image can only be quantised after the whole set of image data is acquired, we propose to use an evolving localised learning model for on-line colour quantisation. This approach is compared with some conventional algorithms.

This is a pedagogical and (almost) self-contained introduction into the Theorem of Groenewold and van Howe, which states that a naive transcription of Dirac’s quantisation rules cannot work. Some related issues in quantisation theory are also discussed. First-class constrained systems a briefly described in a slightly more ‘global’ fashion.1

Depth coding in 3D-HEVC for the multiview video plus depth (MVD) architecture (i) deforms object shapes due to block-level edge-approximation; (ii) misses an opportunity for high compressibility at near-lossless quality by failing to exploit strong homogeneity (clustering tendency) in depth syntax, motion vector components, and residuals at frame-level; and (iii) restricts interactivity and lim...