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We propose a new compression method devoted to large structured hexahedral meshes having discontinuities. It is dedicated to applications such as visualization or physical simulations whose management by any workstation or mobile device with limited memory and bandwidth is critical. Our method relies on a multiresolution analysis that generates a hierarchy of meshes at increasing resolutions. Our...
We propose an algorithm that accomplishes transform-coded, spatiotemporal, pel-recursive video compression. Traditional pel-recursive coders obtain sophisticated spatio-temporal predictions for the current pixel based on previously decoded data. The resulting per-pixel prediction errors are encoded independently so that the decoder can use previously-encoded pixels in the prediction of the current...
This paper introduces a novel class of transforms, called graph-based separable transforms (GBSTs), based on two line graphs with optimized weights. For the optimal GBST construction, we formulate a graph learning problem to design two separate line graphs using row-wise and column-wise residual block statistics, respectively. We also analyze the optimality of resulting separable transforms for both...
Real-time operation and low-power dissipation in video coding systems have become important research challenges, especially in mobile devices with limited battery and computational resources. There are many video coding standards coexisting in the market nowadays, so it is important for current devices to support different video coding standards. This paper presents a multi-standard luminance sub-samples...
Our challenge is the design of a “universal” bit-efficient image compression approach. The prime goal is to allow reconstruction of images with high quality. In addition, we attempt to design the coder and decoder “universal”, such that MPEG-7-like low-and mid-level descriptors are an integral part of the coded representation. To this end, we introduce a sparse Mixture-of-Experts regression approach...
Subjective experimental results are widely used as the ground truth in objective Image Quality Assessment (IQA). Specifically, Pairwise Comparison method has superiority over Mean Opinion Scores (MOS), but there is a problem when measuring the consistency between subjective pairwise comparisons and objective quality predictions. In this paper, we first analyze the existing problem of current evaluation...
We introduce a constant luminance HDR video coding pipeline, which converts the source video to linear Y u'v' color space and applies a dedicated chromaticity transformation before encoding. This reduces perceivable color artifacts without modifying the core codec itself. We validate our approach by a user study that shows a significant improvement in perceived color quality at high compression rates...
The upcoming JPEG XT standard for High Dynamic Range (HDR) images defines a common framework for the lossy and lossless representation of high-dynamic range images. It describes the decoding process as the combination of various processing tools that can be combined freely. In this paper we analyze the coding efficiency of different decoding tools through a large scale objective quality testing using...
This paper studies the influence of JPEG-XT on LDR generation using TMOs'. JPEG-XT encodes HDR images into a two layer scheme, encoding a LDR version of the image in a base layer, and the residual HDR information in an enhancement layer. The question addressed here is to understand if this model allows to extract a new LDR representation using a different TMO, independently of the TMO used to generate...
Earlier research has shown the efficacy of using geometry discontinuities, encoded using “breakpoints,” in improving the coding efficiency of piecewise smooth media, such as depth maps and motion flows. This work proposes a new structure for encoding these breakpoints that is more suited for piecewise affine media, such as affine motion flows. Here, we choose to employ belief propagation over a graphical...
Aiming at understanding the role of short-term memory in subjective image quality assessment, we report and compare results from two pair-comparison methods: stimuli shown side-by-side versus stimuli shown one after the other. Our results suggest that there is a significant chance that an observer will make different quality assessments in the two setups.
This paper introduces row-column transforms (RCTs) which are 2D non-separable transforms defined with the aid of a set of 1-D linear transforms and a basis ordering permutation. We propose a novel method for the design of row-column transforms that approximate desired complex transforms (such as KLTs, SOTs, etc.) so that most of the performance of the approximated transforms is retained at significantly...
Image forensics using sensor photo-response nonuniformity (PRNU) provides a powerful method for associating an image with the camera that captured the image. To preserve privacy despite the availability of this powerful tool, we present a new framework for image anonymization. We formulate anonymization as a feasibility problem subject to multiple constraints that seek to ensure non-detectability...
Traditional quality estimators evaluate an image's resemblance to a reference image. However, quality estimators are not well suited to the similar but somewhat different task of utility estimation, where an image is judged instead by how useful it would be in comparison to a reference in the context of accomplishing some task. Multi-Scale Difference of Gaussian Utility (MS-DGU), a reduced-reference...
This papers presents an analysis on Active Content Fingerprint (aCFP) for local (patch based) image descriptors. A generalization is proposed, the reduction of the aCFP with linear modulation to a constrained projection problem is shown and the optimal solution is given. The constrained projection problem addresses the linear modulation by a constraint on the properties of the resulting local descriptor...
Blind steganalysis techniques are able to detect the presence of secret messages embedded in digital media files, such as images, video, and audio, with an unknown steganography algorithm. This paper present an image steganalysis method based on Evidential K-Nearest Neighbors (EV-knn). Originality of this work is the use of theoretical framework of Belief functions on different subspaces of features...
Despite its age, JPEG (formally, Rec. ITU-T T.81 — ISO/IEC 10918-1) is still the omnipresent image file format for lossy compression of photographic images. While its rate-distortion performance is not competitive with state-of-the-art schemes like JPEG 2000 or HEVC, manifold techniques have been developed over the years to improve its compression performance. This article provides a short review...
The High Efficiency Video Coding (HEVC) standard includes support for a large range of image representation formats and provides an excellent image compression capability. The High Efficiency Image File Format (HEIF) offers a convenient way to encapsulate HEVC coded images, image sequences and animations together with associated metadata into a single file. This paper discusses various features and...
We present a novel lossless image compression algorithm. It achieves better compression than popular lossless image formats like PNG and lossless JPEG 2000. Existing image formats have specific strengths and weaknesses: e.g. JPEG works well for photographs, PNG works well for line drawings or images with few distinct colors. For any type of image, our method performs as good or better (on average)...
Lossy compression techniques based on multi-component transformation (MCT) can effectively enhance the storage and transmission of whole-slide images (WSIs) without adversely affecting subsequent diagnosis processes. Component transforms that are designed for other types of images or that do not take into account all aspects of the compression algorithm applied on the transformed components yield...
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