5 research outputs found
Neural Image Compression with a Diffusion-Based Decoder
Diffusion probabilistic models have recently achieved remarkable success in
generating high quality image and video data. In this work, we build on this
class of generative models and introduce a method for lossy compression of high
resolution images. The resulting codec, which we call DIffuson-based Residual
Augmentation Codec (DIRAC),is the first neural codec to allow smooth traversal
of the rate-distortion-perception tradeoff at test time, while obtaining
competitive performance with GAN-based methods in perceptual quality.
Furthermore, while sampling from diffusion probabilistic models is notoriously
expensive, we show that in the compression setting the number of steps can be
drastically reduced.Comment: v1: 26 pages, 13 figures v2: corrected typo in first author name in
arxiv metadat
Region-of-Interest Based Neural Video Compression
Humans do not perceive all parts of a scene with the same resolution, but
rather focus on few regions of interest (ROIs). Traditional Object-Based codecs
take advantage of this biological intuition, and are capable of non-uniform
allocation of bits in favor of salient regions, at the expense of increased
distortion the remaining areas: such a strategy allows a boost in perceptual
quality under low rate constraints. Recently, several neural codecs have been
introduced for video compression, yet they operate uniformly over all spatial
locations, lacking the capability of ROI-based processing. In this paper, we
introduce two models for ROI-based neural video coding. First, we propose an
implicit model that is fed with a binary ROI mask and it is trained by
de-emphasizing the distortion of the background. Secondly, we design an
explicit latent scaling method, that allows control over the quantization
binwidth for different spatial regions of latent variables, conditioned on the
ROI mask. By extensive experiments, we show that our methods outperform all our
baselines in terms of Rate-Distortion (R-D) performance in the ROI. Moreover,
they can generalize to different datasets and to any arbitrary ROI at inference
time. Finally, they do not require expensive pixel-level annotations during
training, as synthetic ROI masks can be used with little to no degradation in
performance. To the best of our knowledge, our proposals are the first
solutions that integrate ROI-based capabilities into neural video compression
models.Comment: Updated arxiv version to the camera-ready version after acceptance at
British Machine Vision Conference (BMVC) 202
Innate immune responses of a scleractinian coral to vibriosis
Scleractinian corals are the most basal eumetazoan taxon and provide the biological and physical framework for coral reefs, which are among the most diverse of all ecosystems. Over the past three decades and coincident with climate change, these phototrophic symbiotic organisms have been subject to increasingly frequent and severe diseases, which are now geographically widespread and a major threat to these ecosystems. Although coral immunity has been the subject of increasing study, the available information remains fragmentary, especially with respect to coral antimicrobial responses. In this study, we characterized damicornin from Pocillopora damicornis, the first scleractinian antimicrobial peptide (AMP) to be reported. We found that its precursor has a segmented organization comprising a signal peptide, an acidic proregion, and the C-terminal AMP. The 40-residue AMP is cationic, C-terminally amidated, and characterized by the presence of six cysteine molecules joined by three intramolecular disulfide bridges. Its cysteine array is common to another AMP and toxins from cnidarians; this suggests a common ancestor, as has been proposed for AMPs and toxins from arthropods. Damicornin was active in vitro against Gram-positive bacteria and the fungus Fusarium oxysporum. Damicornin expression was studied using a combination of immunohistochemistry, reverse phase HPLC, and quantitative RT-PCR. Our data show that damicornin is constitutively transcribed in ectodermal granular cells, where it is stored, and further released in response to nonpathogenic immune challenge. Damicornin gene expression was repressed by the coral pathogen Vibrio coralliilyticus. This is the first evidence of AMP gene repression in a host-Vibrio interaction