Lossless Image and Intra-Frame Compression With Integer-to-Integer DST

Video coding standards are primarily designed for efficient lossy compression, but it is also desirable to support efficient lossless compression within video coding standards using small modifications to the lossy coding architecture. A simple approach is to skip transform and quantization, and simply entropy code the prediction residual. However, this approach is inefficient at compression. A more efficient and popular approach is to skip transform and quantization but also process the residual block in some modes with differential pulse code modulation ( DPCM), along the horizontal or vertical direction, prior to entropy coding. This paper explores an alternative approach based on processing the residual block with integer-to-integer (i2i) transforms. I2i transforms can map integer pixels to integer transform coefficients without increasing the dynamic range and can be used for lossless compression. We focus on lossless intra coding and develop novel i2i approximations of the odd type-3 discrete sine transform (ODST-3). Experimental results with the high efficiency video coding (HEVC) reference software show that when the developed i2i approximations of the ODST-3 are used along the DPCM method of HEVC, an average 2.7% improvement of lossless intra frame compression efficiency is achieved over HEVC version 2, which uses only the DPCM method, without a significant increase in computational complexity

Transforms for prediction residuals in video coding

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2010.Cataloged from PDF version of thesis.Includes bibliographical references (p. 135-140).Typically the same transform, the 2-D Discrete Cosine Transform (DCT), is used to compress both image intensities in image coding and prediction residuals in video coding. Major prediction residuals include the motion compensated prediction residual, the resolution enhancement residual in scalable video coding, and the intra prediction residual in intra-frame coding. The 2-D DCT is efficient at decorrelating images, but the spatial characteristics of prediction residuals can be significantly different from the spatial characteristics of images, and developing transforms that are adapted to the characteristics of prediction residuals can improve their compression efficiency. In this thesis, we explore the differences between the characteristics of images and prediction residuals by analyzing their local anisotropic characteristics and develop transforms adapted to the local anisotropic characteristics of some types of prediction residuals. The analysis shows that local regions in images have 2-D anisotropic characteristics and many regions in several types of prediction residuals have 1-D anisotropic characteristics. Based on this insight, we develop 1-D transforms for these residuals. We perform experiments to evaluate the potential gains achievable from using these transforms within the H.264 codec, and the experimental results indicate that these transforms can increase the compression efficiency of these residuals.by Fatih Kamışlı.Ph.D

Reduction of blocking artifacts using side information

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2006.Includes bibliographical references (p. 95-96).Block-based image and video coding systems are used extensively in practice. In low bit-rate applications, however, they suffer from annoying discontinuities, called blocking artifacts. Prior research shows that incorporating systems that reduce blocking artifacts into codecs is useful because visual quality is improved. Existing methods reduce blocking artifacts by applying various post-processing techniques to the compressed image. Such methods require neither any modification to current encoders nor an increase in the bit-rate. This thesis examines a framework where blocking artifacts are reduced using side information transmitted from the encoder to the decoder. Using side information enables the use of the original image in deblocking, which improves performance. Furthermore, the computational burden at the decoder is reduced. The principal question that arises is whether the gains in performance of this choice can compensate for the increase in the bit-rate due to the transmission of side information. Experiments are carried out to answer this question with the following sample system: The encoder determines block boundaries that exhibit blocking artifacts as well as filters (from a predefined set of filters) that best deblock these block boundaries.(cont.) Then it transmits side information that conveys the determined block boundaries together with their selected filters to the decoder. The decoder uses the received side information to perform deblocking. The proposed sample system is compared against an ordinary coding system and a post-processing type deblocking system with the bit-rate of these systems being equal to the overall bit-rate (regular encoding bits + side information bits) of the proposed system. The results of the comparisons indicate that, both for images and video sequences, the proposed system can perform better in terms of both visual quality and PSNR for some range of coding bit-rates.by Fatih Kamisli.S.M

Interactions among Stock Price and Financial Ratios: The Case of Turkish Banking Sector

One of the important variables for investors is the price of stocks and so that the variables that affect the price of the stocks. There are many indicators and methods such as fundamental and technical analysis that investors can use in valuing these instruments. Fundamental analysis, and financial ratios are tools that are generally used in investments process. Especially price-earnings ratio and dividend yield ratio are traditional financial ratios which are used to forecast the performance of the stock. In this context, the purpose of this study is to analyze the relationships between the price, price-earnings ratio and dividend yield ratio of the companies that are listed at BIST Banking sub-sector. In this context, in line with the aim of the study monthly price, price-earnings ratio and dividend yield ratio of VAKBN; ISCTR; HALKB; GARAN; AKBNK stocks between 2008M10-2017M3 will be analyzed by VAR methodology. Results show that the relationships between the abovementioned variables changes in size and direction from bank to bank

Intra prediction based on Markov process modeling of images

In recent video coding standards, intraprediction of a block of pixels is performed by copying neighbor pixels of the block along an angular direction inside the block. Each block pixel is predicted from only one or few directionally aligned neighbor pixels of the block. Although this is a computationally efficient approach, it ignores potentially useful correlation of other neighbor pixels of the block. To use this correlation, a general linear prediction approach is proposed, where each block pixel is predicted using a weighted sum of all neighbor pixels of the block. The disadvantage of this approach is the increased complexity because of the large number of weights. In this paper, we propose an alternative approach to intraprediction, where we model image pixels with a Markov process. The Markov process model accounts for the ignored correlation in standard intraprediction methods, but uses few neighbor pixels and enables a computationally efficient recursive prediction algorithm. Compared with the general linear prediction approach that has a large number of independent weights, the Markov process modeling approach uses a much smaller number of independent parameters and thus offers significantly reduced memory or computation requirements, while achieving similar coding gains with offline computed parameters

Intra Prediction Based on Markov Process Modeling of Images

In recent video coding standards, intraprediction of a block of pixels is performed by copying neighbor pixels of the block along an angular direction inside the block. Each block pixel is predicted from only one or few directionally aligned neighbor pixels of the block. Although this is a computationally efficient approach, it ignores potentially useful correlation of other neighbor pixels of the block. To use this correlation, a general linear prediction approach is proposed, where each block pixel is predicted using a weighted sum of all neighbor pixels of the block. The disadvantage of this approach is the increased complexity because of the large number of weights. In this paper, we propose an alternative approach to intraprediction, where we model image pixels with a Markov process. The Markov process model accounts for the ignored correlation in standard intraprediction methods, but uses few neighbor pixels and enables a computationally efficient recursive prediction algorithm. Compared with the general linear prediction approach that has a large number of independent weights, the Markov process modeling approach uses a much smaller number of independent parameters and thus offers significantly reduced memory or computation requirements, while achieving similar coding gains with offline computed parameters

Block-Based Spatial Prediction and Transforms Based on 2D Markov Processes for Image and Video Compression

Conventional intraframe coding is performed in two steps. First, a block of pixels are predicted by copying previously reconstructed neighbor pixels of the block along an angular direction inside the block. Then, the prediction residual block is transform coded with the well-known 2D discrete cosine transform (DCT). Recently, it has been shown that transforming the intraprediction residuals with the odd type-3 discrete sine transform along the prediction direction and the DCT along the perpendicular direction improves the compression performance. More recently, a recursive prediction approach has been proposed to improve intra prediction performance. Both of these recent approaches utilize Markov processes to develop improvements in either the transform or the prediction step but not in both. In this paper, both the intraprediction and the transform steps are obtained based on 2D Markov processes. The derived overall intraframe coding approaches can generalize the mentioned two approaches, provide improved coding gains and produce less blocking effects at low bitrates

Recursive Prediction for Joint Spatial and Temporal Prediction in Video Coding

Video compression systems use prediction to reduce redundancies present in video sequences along the temporal and spatial dimensions. Standard video coding systems use either temporal or spatial prediction on a per block basis. If temporal prediction is used, spatial information is ignored. If spatial prediction is used, temporal information is ignored. This may be a computationally efficient approach, but it does not effectively combine temporal and spatial information. In this letter, we provide a framework where available temporal and spatial information can be combined effectively to perform joint spatial and temporal prediction in video coding. Experimental results obtained from one sample realization of this framework show its potential

Intra prediction based on statistical modeling of images

Intra prediction is an important part of intra-frame coding. A number of approaches have been proposed to improve intra prediction including a general linear prediction approach in which a weighted sum of all available neighbor pixels is used to predict each block pixel. An important part of this approach is the determination of the used weights. One method to determine the weights is to use the least-squares solution of an overdetermined linear system of weights. In this paper, we present an alternative approach where the weights are determined based on statistical modeling of image pixels. This approach results in an analytical expression for the weights and can achieve similar coding gains as methods based on least-squares solutions of overdetermined systems, while having several benefits such as reduced storage or computations

A low-complexity image compression approach with single spatial prediction mode and transform

The well-known low-complexity JPEG and the newer JPEG-XR systems are based on block-based transform and simple transform-domain coefficient prediction algorithms. Higher complexity image compression algorithms, obtainable from intra-frame coding tools of video coders H.264 or HEVC, are based on multiple block-based spatial-domain prediction modes and transforms. This paper explores an alternative low-complexity image compression approach based on a single spatial-domain prediction mode and transform, which are designed based on a global image model. In our experiments, the proposed single-mode approach uses an average 20.5 % lower bit-rate than a standard low-complexity single-mode image coder that uses only conventional DC spatial prediction and 2-D DCT. It also does not suffer from blocking effects at low bit-rates