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Common e-commerce websites rely heavily on JPEG images for product presentation. In this paper we present a new coding scheme and file format that is tailored to the presentation of single-color products. A JPEG image file can be transcoded into this new format leading to substantial reduction in file size (Average of 28%) with practically no quality degradation. We describe how we can take advantage...
The paper describes a highly efficient coding scheme based on the Complete Oscillator Method (COM). The COM has a number of powerful theoretical properties which enable it to provide very compact models for a wide range of deterministic signals. Several of these properties are studied here. The theoretical COM is shown to model and synthesize exactly all types of stationary signals, irrespective of...
This paper presents an innovative and efficient approach to code compression. Our method reduces code size by up to 32.6% and 31.9% (including all extra costs) respectively, for ARM and MIPS processor, and presents an improvement of almost 7% over the traditional Huffman method. We performed simulations and analyzes, using the applications from benchmark MiBench. In spite of these experiments, our...
In its Paris meeting, the JPEG committee decided to work on a backwards compatible extension of the popular JPEG (10918-1) standard enabling lossy and lossless coding of high-dynamic range (HDR) images, the new standard shall allow legacy applications to decompress new code streams into a tone mapped version of the HDR image while codecs aware of the extensions will decompress the stream with full...
In this paper, we present efficient algorithms for interconversion between Lempel-Ziv 78 (LZ78) encoding and run length encoding (RLE). We show how, given an RLE of size n for a string S, we can compute the corresponding LZ78 encoding of size m for S in O((n + m) log Ð) time, where Ð is the number of distinct characters appearing in S. We also show how, given an LZ78 encoding...
We present a simple adaptation of the Lempel Ziv 78' (LZ78) compression scheme that supports efficient random access to the input string. The compression algorithm is given as input a parameter $\eps >0$, and with very high probability increases the length of the compressed string by at most a factor of $(1+\eps)$. The access time is $O(\log n + 1/\eps^2)$ in expectation, and $O(\log n/\eps^2)$...
The Re-Pair algorithm proposed by Larsson and Moffat in 1999 is a simple grammar-based compression method that achieves an extremely high compression ratio. However, Re-Pair is an offline and very space consuming algorithm. Thus, to apply it to a very large text, we need to divide the text into smaller blocks. Consequently, if we share a part of the dictionary among all blocks, we expect that the...
Transform coding using the discrete cosine transform (DCT) has been widely used in image and video coding standards. But at low bit rates, the coded images suffer from severe visual distortions such as blocking artifacts. Image deblocking techniques can reduce these distortions and alleviate the conflict between bit rate reduction and visual quality preservation. In this paper, we propose a novel...
This paper presents a low-complexity approach to deriving Region Of Interest vectors for an image based on fast sorting and histogram binning indexed by the components of the vector. Using the ROI vector list as guidance, a motion estimation algorithm can go through the motion vector field for the frame and align vectors with high global cost to the ROI vectors. This technique reduces global cost...
In this paper we discuss data structures and algorithms for linear time encoding and decoding of minimum redundancy codes. We show that a text of length over an alphabet of cardinality can be encoded to minimum redundancy code and decoded from minimum redundancy code in time $O(n)$ using only an additional space of $O(\sigma)$ words ($O(\sigma\log n)$ bits) for handling the auxiliary data...
The problem of performing similarity queries on compressed data is considered. We study the fundamental tradeoff between compression rate, sequence length, and reliability of queries performed on compressed data. For a Gaussian source and quadratic similarity criterion, we show that queries can be answered reliably if and only if the compression rate exceeds a given threshold - the identification...
This paper describes a scalable video codec that was submitted as a response to the joint call for proposals issued by ISO/IEC MPEG and ITU-T VCEG on HEVC scalable extension. The proposed codec uses a multi-loop decoding structure. Several inter-layer texture prediction methods are employed to remove the inter-layer redundancy. Inter-layer prediction is also used when coding enhancement layer syntax...
Motion information in image sequences connects pixels that are highly correlated. In this paper, we consider vertex-weighted graphs that are formed by motion vector information. The vertex weights are defined by scale factors which are introduced to improve the energy compaction of motion-adaptive transforms. Further, we relate the vertex-weighted graph to a subspace constraint of the transform. Finally,...
In this paper, we present an improved algorithm for decoding live streamed or pre-encoded video bit streams with time-varying qualities. The algorithm extracts information available to the decoder from a high visual quality segment of the clip that has already been received and decoded, but was encoded independently from the current segment. The proposed decoder is capable of significantly improve...
Distributed video coding (DVC) has been intensively studied in recent years. This new coding paradigm substantially differs from conventional prediction-based video codecs such as MPEG and H.26x, which are characterized by a complex encoder and simple decoder. The conventional DVC codec, e.g., DISCOVER codec, uses advanced frame interpolation techniques to create SI based on adjacent decoded reference...
This paper proposes a Multi-Symbol Context Adaptive Binary Arithmetic Coding (CABAC) Framework in Hybrid Video Coding. Advanced CABAC techniques have been employed in popular video coding technologies like H264-AVC, HEVC. The proposed framework aims at extending these technique by providing symbol level scalability in being able to code one or multi-symbols at a time without changing the existing...
LZ77-based compression schemes compress the input text by replacing factors in the text with an encoded reference to a previous occurrence formed by the couple (length, offset). For a given factor, the smallest is the offset, the smallest is the resulting compression ratio. This is optimally achieved by using the rightmost occurrence of a factor in the previous text. Given a cost function, for instance...
This paper considers the problem of universal lossless source coding with side information at the decoder only. The correlation channel between the source and the side information is unknown and belongs to a class parametrized by some unknown parameter vector. A complete coding scheme is proposed that works well for any distribution in the class. At the encoder, the proposed scheme encompasses the...
The new demands for high resolution digital video applications are pushing the development of new techniques in the video coding area. This paper presents a simplified version of the original Fractional Motion Estimation (FME) algorithm defined by the HEVC emerging video coding standard targeting a low cost and high throughput hardware design. Based on evaluations using the HEVC Model (HM), the HEVC...
The paper describes a scalable video coding extension of the upcoming HEVC video coding standard for spatial and quality scalable coding. Besides coding tools known from scalable profiles of prior video coding standards, it includes new coding tools that further improve the enhancement layer coding efficiency. The effectiveness of the proposed scalable HEVC extension is demonstrated by comparing the...
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