Recent progress in video compression is seemingly reaching its limits making it very hard to improve coding efficiency significantly further. The adaptive loop filter (ALF) has been a topic of interest for many years. ALF reaches high coding gains and has motivated many researchers over the past years to further improve the state-of-the-art algorithms. The main idea of ALF is to apply a classification to partition the set of all sample locations into multiple classes. After that, Wiener filters are calculated and applied for each class. Therefore, the performance of ALF essentially relies on how its classification behaves. In this paper, we extensively analyze multiple feature-based classifications for ALF (MCALF) and extend the original MCALF by incorporating sample adaptive offset filtering. Furthermore, we derive new block-based classifications which can be applied in MCALF to reduce its complexity. Experimental results show that our extended MCALF can further improve compression efficiency compared to the original MCALF algorithm.

In this paper we combine video compression and modern image processing methods. We construct novel iterative filter methods for prediction signals based on Partial Differential Equation (PDE)-based methods. The central idea of the signal adaptive filters is explained and demonstrated geometrically. The meaning of particular parameters is discussed in detail. Furthermore, thorough parameter tests are introduced which improve the overall bitrate savings. It is shown that these filters enhance the rate-distortion performance of the state-of-the-art hybrid video codecs. In particular, based on mathematical denoising techniques, two types of diffusion filters are constructed: a uniform diffusion filter using a fixed filter mask and a signal adaptive diffusion filter that incorporates the structures of the underlying prediction signal. The latter has the advantage of not attenuating existing edges while the uniform filter is less complex. The filters are embedded into a software based on HEVC with additional QTBT (Quadtree plus Binary Tree) and MTT (Multi-Type-Tree) block structure. Overall, the diffusion filter method achieves average bitrate savings of 2.27% for Random Access having an average encoder runtime increase of 19% and 17% decoder runtime increase. For UHD (Ultra High Definition) test sequences, bitrate savings of up to 7.36% for Random Access are accomplished.

With Version 2 of the high-efficiency video coding standard, a new compression efficiency tool targeting redundancies among color components is specified for all 4:4:4 profiles, and referred to as cross-component prediction (CCP). This paper describes and analyses two additional extensions to the specified CCP variant. In the first extension, an additional predictor is introduced. Particularly, beside the luma component, also the first chroma component can serve as a reference for prediction of the second chroma component. The second extension proposes a method for predicting the CCP model parameter from the statistics of already reconstructed neighboring blocks. A performance analysis of coding RGB content in different color representations is given in comparison with CCP and both extensions. Experimental results show that the proposed extensions can improve the compression efficiency effectively compared with CCP, when applied in the YCbCr domain.

More frequent and severe algal blooms are symptomatic of increasing ecosystem stress in coastal waters. Economic losses typically follow and local governments are forced to ‘manage’ this issue. Because many blooms are not monitored, local ecological knowledge (LEK) and oral history are the only practical tools to obtain data on bloom characteristics and identify their drivers. LEK was applied to outbreaks of brown algae on popular tourist beaches in south-east Queensland (Australia). Structured interviews with local citizens who had a close and frequent connection with the ocean provided 541 bloom records, which showed that blooms are regional (≥400 km) rather than local, and that they are a historical (≥40 years) rather than a recent phenomenon. LEK frequently cited that particular wind regimes coincided with the arrival of blooms, but this could not be verified by statistical cross-validation with empirical data. Harnessing LEK was valuable in engaging citizens, in generating testable hypotheses about plume causes, in providing a previously unrecognized historical perspective and in identifying the correct spatial scale of the issue. Multi-pronged approaches will be most effective in addressing blooms where local mitigation actions are combined with broader regional coastal environmental conservation efforts.

Recall that a ring R (all rings considered are commutative with unit) is an elementary divisor ring (respectively, a Hermite ring) provided every matrix over R is equivalent to a diagonal matrix (respectively, a triangular matrix). Thus, every elementary divisor ring is Hermite, and it is easily seen that a Hermite ring is Bezout, that is, finitely generated ideals are principal. Examples have been given [4] to show that neither implication is reversible.