Picture Coding Research Articles

A new adaptive approach to picture coding

A new adaptive approach to picture coding

A new construction of two-dimensional arrays with the window property

It is shown how row-complete Latin squares and Tuscan squares can be used to construct nonbinary 1-D and 2-D arrays that have the u*v horizontal and/or vertical window property for all sufficiently large windows. It is shown how binary arrays with a similar property can be derived. Since an array can only be a perfect map for one particular size of window, the arrays that are constructed are not perfect but nevertheless have several practical applications, among others in connection with the coding and transmission of pictures. The method is deterministic rather than stochastic, and the arrays derived contain an effectively random selection of the windows of each relevant size.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

講座 画像情報圧縮の手ほどき 第９回 静止画像の符号化方式

講座 画像情報圧縮の手ほどき 第９回 静止画像の符号化方式

A Standard for Interactive Video

Several Digital Storage Media such as compact disk and DAT offer the possibility of interactive video applications. The bandwidth of these storage media is still inadequate to handle digital video combined (combined with audio) without sophisticated, high efficiency redundancy reduction techniques. Standards in this area are essential to the development of the related hardware and software industry. The development of an ISO standard in this area is being pursued by a Moving Picture Coding Expert Group (MPEG) with the target of a draft proposal for the standardization of the coded representation of moving images and audio information to be completed by September 1990. This paper describes the status of the work within MPEG.

A 24-b 50-ns digital image signal processor

A 50-ns digital image signal processor (DISP)-an image/video application-specific VLSI chip-is discussed. This chip integrates 538 K transistors and dissipates 1.4 W at a 40-MHz clock. It is based on a 24-b fixed-point architecture with a five-stage pipeline. The DISP features a real-time processing capability realized by an enhanced parallel architecture, video-oriented data processing functions, and an instruction cycle time that is typically 35 ns, and 50 ns at worst. This 50-ns cycle time allows the DISP to execute mor than 60-million operations per second (MOPS). High-density 1.0- mu m CMOS technology allows numerous on-chip features, including specified resources optimized for image processing. This allows a flexible hardware implementation of various algorithms for picture coding. Several circuit design techniques that are intended to attain a fast instruction cycle are reviewed, including distributed instruction decoding and a hierarchical clocking circuit. The LSI has been designed by the extensive use of a cell-based design method. The processor incorporates a sophisticated testing function compatible with a cell-based design environment.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Image coding using an adaptive sampling technique

We propose a spatial frequency bandwidth estimation applied to perform an adaptive picture coding. The local bandwidth estimation is derived from the Bernstein inequality and is used to achieve an adaptive image resampling. The picture is then reconstructed through interpolation and the results compared with those of more usual coding processes.

Statistics of video signals for viewphone-type pictures

The authors describe a series of measurements of the statistics of viewphone-type video signals, with particular regard to the possible transmission of such signals over an asynchronous transfer mode (ATM) network. Measurements include the frame-to-frame differences and the cluster length distribution. It is known that with efficient picture coding, the information rate required for a constant picture quality varies significantly and creates problems in a constant-bit-rate system. The multiplexing of a number of sources in a variable-bit-rate (VBR) system is considered. It is shown that considerable reduction in the variability of the data rate is obtained. While the results are derived from one particular type of picture coder, it is expected that the conclusion will apply to other coding schemes. >

Use of recursive binary nesting for coding moving image sequences

Recursive binary nesting (RBN) is a quadtree-based interpolation technique originally developed for still picture coding, which we have modified efficiently to code moving sequences. When the basic technique is used for motion coding, visually disturbing effects occur. The causes of these are identified and the algorithm modified to remove them.

PROGRESS IN HIGH COMPRESSION IMAGE CODING

The digital representation of an image requires a very large number of bits. The goal of image coding is to reduce this number, as much as possible, and to reconstruct a faithful duplicate of the original picture. Early efforts in image coding, solely guided by information theory, led to a plethora of methods. The compression ratio reached a plateau around 10: 1 a couple of years ago. Recent progress in the study of the brain mechanism of vision and scene analysis has opened new vistas in picture coding. Directional sensitivity of the neurones in the visual pathway combined with the separate processing of contours and textures has led to a new class of coding methods capable of achieving compression ratios as high as 100: 1. This paper presents recent progress on some of the main avenues of object-based methods. These second generation techniques make use of contour-texture modeling, new results in neurophysiology and psychophisics and scene analysis.

Recent results in high-compression image coding (Invited Papaer)

The digital representation of an image requires a very large number of bits. The goal of image coding is to reduce this number as much as possible, and to reconstruct a faithful duplicate of the original picture. Early efforts in image coding, solely guided by information theory, led to a plethora of methods. The compression ratio reached a plateau of about 10:1 several years ago. Recent progress in the study of the brain mechanism of vision and of scene analysis has opened new vistas in picture coding. The concept of directional sensitivity of neurones in the visual cortex combined with the separate processing of contours and textures has led to a new class of coding methods, called second generation, capable of achieving compression ratios as high as 100:1. In this paper, recent results on object-based coding methods are reported, exhibiting improvements in the previous second-generation methods.

Some results on two-dimensional pseudoquadrature mirror filters

One-dimensional (1-D) pseudoquadrature mirror filters (PQMF's) have been introduced as a generalization of quadrature mirror, filter (QMF) concepts. Use of such filters allows one to split directly the spectrum of an input signal into <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">N</tex> equally spaced subbands which can be decimated by <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">N: 1</tex> , then interpolated and recombined to reproduce the original signal. In this paper, a detailed derivation of conditions specifying 2-D PQMF design constraints for a distortion-free (i.e., aliasing and amplitude distortions) reconstruction of the original signal are obtained. Potential applications for such filters include efficient subband coding of digital pictures.

Conditional Run-Length and Variable-Length Coding of Digital Pictures

In earlier publications, we have presented two coding schemes which take into account the conditional statistics of input signals. In the first scheme, the codewords are assigned in such a way as to provide a signal with long runs of zeros and ones. In the second scheme, each picture element is coded by variable-length codewords according to the values of previously transmitted PEL's. In this paper, by providing further results, we examine these coding schemes in greater detail. The performance of both schemes in terms of entropy and bit rate are compared with an optimum predictive coder. The simulation results indicate that these schemes have a significant advantage over standard predictive encoders. Methods to reduce the storage requirement for the encoder and decoder codebooks are also discussed.

A hybrid Hadamard LPC scheme for picture coding

A transform-LPC hybrid system for real-time coding of picture data has been presented. The LPC has been made adaptive by using a correlation cancellation loop. Three different schemes for coding and reconstructing the transform components have been presented and their relative performances have been compared. The MSE and SNR are seen to be comparable to previous work on transform-DPCM hybrid schemes.

カラー静止画像符号化方式の国際標準化

カラー静止画像符号化方式の国際標準化

A New Halftone Reproduction and Transmission Method Using Standard Black and White Facsimile Code

This paper proposes an adaptive dithering method, which can reproduce grey levels with good character quality. It also proposes dither threshold patterns with long run-length, which are able to obtain a compression ratio of about 3 or 4 when using modified Huffman coding schemes. The method presented here is applicable to facsimile equipment for transmitting pictures, including both continuoustone pictures and characters, using CCITT standard black and white picture coding.

Colour Picture Coding - Algorithm Optimization and Technical Realization

Colour Picture Coding - Algorithm Optimization and Technical Realization

AN Edge Enhancement Algorithm Using a Polynomial Transformation

The paper describes a new algorithm proposed for improving the subjective quality of picture by means of contour enhancement. The method applies on digitalized pictures. The algorithm is based on a transient detection scheme followed by a polunomial transformation. The possibility of choosing a specific polynomial makes this new method useful for various applications, such as chrominance contour improvement on television pictures or edge enhancement for picture coding.

Progressive Coding and Transmission of Digital Diagnostic Pictures

In radiology, as a result of the increased utilization of digital imaging modalities, such as computed tomography (CT) and magnetic resonance imaging (MRI), over a third of the images produced in a typical radiology department are currently in digital form, and this percentage is steadily increasing. Image compression provides a means for the economical storage and efficient transmission of these diagnostic pictures. The level of coding distortion that can be accepted for clinical diagnosis purposes is not yet well-defined. In this paper we introduce some constraints on the design of existing transform codes in order to achieve progressive image transmission efficiently. The design constraints allow the image quality to be asymptotically improved such that the proper clinical diagnoses are always possible. The modified transform code outperforms simple spatial-domain codes by providing higher quality of the intermediately reconstructed images. The improvement is 10 dB for a compression factor of 256:1, and it is as high as 17.5 dB for a factor of 8:1. A novel progressive quantization scheme is developed for optimal progressive transmission of transformed diagnostic images. Combined with a discrete cosine transform, the new approach delivers intermediately reconstructed images of comparable quality twice as fast as the more usual zig-zag sampled approach. The quantization procedure is suitable for hardware implementation.

Image Compression Using Adaptive Vector Quantization

The paper demonstrates the application of adaptive vector quantization techniques to the coding of monochromatic and color pictures. Codebooks of representative vectors are generated for different portions of the image. By means of extensive simulations, the performance of the coder for monochrome images is estimated as a function of the various coding parameters-vector dimensionality, number of representative vectors, and degree of adaptivity. It is shown that for a vector size of dimension 4, there is a zone of operation, ranging from 1.0 to 1.5 bits/pixel, where adaptive vector quantization is advantageous. Despite the simplicity of the decoder, the performance of the adaptive vector quantizer is found to be comparable with block transform coding schemes for both monochrome and color pictures.

Picture coding by an adaptive multistage vector quantization

AbstractAn adaptive multistage vector quantizing system is proposed for highly efficient picture coding method and its coding performances are investigated. This system contains a multistage vector quantizer which means that comparatively large picture blocks are quantized first, then the remaining quantization error is quantized in smaller blocks, gradually refining the resolution at subsequent stages. That is, a rough picture is coded first and finer structures are coded later. Computer simulation studies on several picture samples demonstrate the excellent processing efficiency of the proposed method in comparison with conventional vector quantizers.