Showing papers on "JPEG 2000 published in 1994"

Rate-distortion optimal fast thresholding with complete JPEG/MPEG decoder compatibility

Abstract: We show a rate-distortion optimal way to threshold or drop the DCT coefficients of the JPEG and MPEG compression standards. Our optimal algorithm uses a fast dynamic programming recursive structure. The primary advantage of our approach lies in its complete compatibility with standard JPEG and MPEG decoders. >

Wavelet-based post-processing of low bit rate transform coded images

Abstract: We propose a novel method based on wavelet thresholding for enhancement of decompressed transform coded images. Transform coding at low bit rates typically introduces artifacts associated with the basis functions of the transform. In particular, the method works remarkably well in "deblocking" of DCT compressed images. The method is nonlinear, computationally efficient, and spatially adaptive and has the distinct feature that it removes artifacts yet retain sharp features in the images. An important implication of this result is that images coded using the JPEG standard can efficiently be postprocessed to give significantly improved visual quality in the images. The algorithm can use a conventional JPEG encoder and decoder for which VLSI chips are available. >

Image coding by use of discrete cosine transforms

Abstract: Image coding methods and apparatus employing discrete cosine transforms for supressing and/or reducing blocking artifacts using a JPEG file format. The methods can be implemented on JPEG hardware slightly modified to provide access to discrete cosine transform coefficients. Filtering techniques by which an overlap procedure for implementing the inventive methods are also disclosed.

Wavelet transforms in a JPEG-like image coder

Abstract: The discrete wavelet transform is incorporated into the JPEG baseline coder for image coding. The discrete cosinetransform is replaced by an association of two-channel filter banks connected hierarchically. The scanning andquantization schemes are devised and the entropy coder used is exactly the same as used in JPEG. The result isa still image coder that outperforms JPEG while retaining its simplicity and most of its existing building blocks.Objective results and reconstructed images are presented.Keywords: image coding, wavelet transform, JPEG. 1 Introduction The discrete cosine transform (DCT) [1] plays a major role in the popular image data compressors and DCT basedalgorithms are widely available nowadays. In still image compression, the JPEG baseline coder (JPEG) [2] is a "defacto" standard and there are several chips and programs available to perform JPEG compression and decompression.JPEG is based on the DCT, because of the DCT's fast implementation algorithm allied with good performance.

Statistical distribution of DCT coefficients and their application to an adaptive compression algorithm

Abstract: The paper presents a technique for image compression using the Discrete Cosine Transform (DCT) method. In the Joint Photographic Expert Group norm (JPEG), the image is usually compressed using an "universal" quantization matrix. We propose a technique which employs an appropriate distribution model of the DCT coefficients to deduce the quantization matrix from a set of training images. This technique compared to the classical JPEG gave no blocking effect at the same compression rate. >

Application of fuzzy controller to JPEG

Abstract: An application of a fuzzy controller to JPEG for (grey-scale) image data compression is presented. The fuzzy controller conducts the search for a better compromise between compression ratio and image quality automatically in the JPEG model. Therefore, the fuzzy controller equipped JPEG is insensitive to the given initial quality. Simulations are performed on the image Lena and the results indicate that this fuzzy control equipped JPEG is very promising. >

Customized JPEG compression for grayscale printing

Abstract: Describes a procedure by which JPEG compression may be customized for grayscale images that are to be compressed, halftoned, and printed. The technique maintains 100% compatibility with the JPEG standard, and is applicable with any halftoning algorithm. The JPEG quantization table is designed using frequency-domain characteristics of the halftoning patterns and the human visual system, and the Huffman tables are optimized for low-rate coding. The authors present experimental results demonstrating that the customized JPEG encoder offers a significant performance advantage over a coder that uses the default quantization and Huffman tables. The results also show that the customized encoder typically achieves rates in the range 0.13-0.25 bits per pixel (image dependent) with practically no visible compression artifacts in the printed images. >

Scalable compression for image browsing

Abstract: We present scalable compression algorithms for image browsing. Recently, the International Standards Organization (ISO) has proposed the JPEG standard for still image compression. JPEG standard not only provides the basic feature of compression (baseline algorithm) but also provides the framework for reconstructing images in different picture qualities and sizes. These features are referred to as SNR and spatial scalability, respectively. SNR scalability and spatial scalability can be implemented using the progressive and hierarchical modes in the JPEG standard. In this paper, we implement and investigate the performance of the progressive and hierarchical coding modes of the JPEG standard and compare their performance with the baseline algorithm. >

Low-bit-rate image compression evaluations

Abstract: In order to assist the National Imagery Transmission Format Standard (NITFS) Technical Board (NTB) in selecting new BWC algorithm(s), evaluations of candidate image compression algorithms were performed on the basis of objective and subjective image quality performance, bit rate control, susceptibility to channel errors, and complexity of implementation. Based on these evaluations, which were conducted under the guidance of the NTB, it was concluded that the ISO/JPEG DCT compression algorithm was the most suitable for the NITFS purpose even though two proprietary sub-band coding techniques generally performed better in subjective image quality. Moreover, it was decided that three algorithms would be further evaluated at very low bit rates where the ISO/JPEG DCT does not perform optimally.

Radiological image compression using wavelet transform with arithmetic coding

Abstract: We have developed a compression algorithm based on discrete wavelet transform (DWT) and arithmetic coding (AC) that satisfies the requirements of a radiological image archive. This new method is far superior to the previously developed full frame DCT (FFDCT) method as well as the industrial standard JPEG. Since DWT is localized in both spatial and scale domains, the error due to quantization of coefficients does not propagate throughout the reconstructed picture as in FFDCT. Since it is a global transformation, it does not suffer the limitation of block transform methods like JPEG. The severity of error as measured by NMSE and maximum difference increases very slowly with compression ratio compared to FFDCT. Normalized nearest neighbor difference (NNND), which is a measure of blockiness, stays approximately constant, while JPEG's NNND increases rapidly with compression ratio. Furthermore, DWT has an efficient FIR implementation which can be put in parallel hardware. DWT also offers total flexibility in the image format; the size of the image does not have to be a power of two as in the case of FFDCT.© (1994) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Quantization table design for JPEG compression of angiocardiographic images

Abstract: The lossy JPEG standard may be used for high performance image compression. As implemented in presently available hard- and software in most cases the so-called luminance quantization table is applied for gray level images, which may be scaled by a quality factor. The questions arise which quality factor is optimal and whether it is possible and worthwhile to specify quantization tables for the particular characteristics of angiocardiograms. Two new quantization tables are derived from the transfer function of the angiocardiographic system, which is a worst-case approach with respect to preserving sharp edges. To assess the performance, evaluations based on Hosaka-plots are developed. These diagrams compare the different errors introduced by lossy JPEG compression objectively. >

Simulated annealing applied to optimal dct quantization

Abstract: We present a method for determining optimum quantization tables for use in image compression systems which conform to the ISO/CCITT standard for Image Compression, also known as the Joint Photographic Experts Group (JPEG) standard1. An algorithm based on simulated annealing2 compresses and decompresses any collection of 8 by 8 pixel blocks, while searching the space of 8 by 8 quantization tables for optimum fidelity according to some chosen measure. A composite cost function maintains a predefined compression ratio while minimizing the RMS error in the decoded image compared to the original. The process can be carried out on a raw image, or greater weight can be given to a selected range of DCT coefficients on the basis of psychophysical considerations3. The results of applying the methods to the intensity (y) components of three JPEG test images are presented. In all cases improved fidelity as measured by RMS error is obtained compared to the quantization table suggested in the JPEG standard. Significantly, the quantization tables obtained for one image most often provide smaller error when applied to other images than does the table suggested with the JPEG standard. An unexpected result when using pre-emphasized images suggests that the psychophysical assumptions underlying the suggested JPEG table may be oversimplified. By applying the method to blocks selected from a variety of images, improved quantization tables can be found for images in general, including color.

Design of a motion JPEG (M/JPEG) adapter card

Abstract: In this paper we describe a design of a high performance JPEG (Joint Photographic Experts Group) Micro Channel adapter card. The card, tested on a range of PS/2 platforms (models 50 to 95), can complete JPEG operations on a 640 by 240 pixel image within 1/60 of a second, thus enabling real-time capture and display of high quality digital video. The card accepts digital pixels for either a YUV 4:2:2 or an RGB 4:4:4 pixel bus and has been shown to handle up to 2.05 MBytes/second of compressed data. The compressed data is transmitted to a host memory area by Direct Memory Access operations. The card uses a single C-Cube's CL550 JPEG processor that complies with the baseline JPEG. We give broad descriptions of the hardware that controls the video interface, CL550, and the system interface. Some critical design points that enhance the overall performance of the M/JPEG systems are pointed out. The control of the adapter card is achieved by an interrupt driven software that runs under DOS. The software performs a variety of tasks that include change of color space (RGB or YUV), change of quantization and Huffman tables, odd and even field control and some diagnostic operations.© (1994) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Image communication services using JPEG

Abstract: Personal Computer (PC) users have recently wished to use image data. Such data is usually compressed for easy handling because of its enormous amount. JPEG, an international standard for color image coding, involves widespread use of images in communications. This paper presents full-color image communication using JPEG with its effective usage. The authors have developed a personal computer image communication terminal, which consists of a PC and a CODEC board as hardware and an image database allowing users to design their own image and text layout on the terminal. The CODEC board is required to achieve JPEG coding scheme and to display a full-color image on the PC screen

Experiments with a Lossless JPEG Codec

Abstract: The ISO JPEG Still Image Compression Standard is popularly known for its DCT-based compression technique, but its non-DCT based lossless mode of operation is less well known. Lossless JPEG uses a form of discrete pulse code modulation (DPCM) [3]. That is, a linear combination of a pixel’s left, upper and upper left neighbors is used to predict the pixel’s value, and the difference between the pixel and its predictor is coded through either Huffman or Arithmetic coding. Lossless JPEG defines seven linear combination known as prediction selection values (PSV).

JPEG-based image compression scheme using fully decomposed wavelet packet transform

Abstract: The block DCT transform plays an important role in the JPEG still image compression standard. In this research, we investigate the replacement of the DCT block transform in the JPEG with the fully-decomposed wavelet packet transform while keeping all other building blocks the same with the objective to improve the performance of the JPEG. Different wavelet packet bases have been used in experiments. Most of them give better performance than that of the DCT-based JPEG scheme in the mean square error measure as well as visual appearance.

Low-bit-rate compression using recursive block coding techniques

Abstract: The hybrid JPEG/recursive block coding (JPEG/RBC) algorithm introduced in [1] consid-erably reduces the tile effect and produces visually pleasing images. This paper proposes its usein low bit rate image coding and presents a quantization matrix (QM) design for the DST blocks that can be used for a wide range of low DST bit rates. The data rate optimization problem encountered in the JPEG/RBC algorithm is discussed and an empirical ratio of the bit rates forthe DCT and the DST blocks is obtained for low bit rate image coding. Subjective evaluation [2] of images coded at low bit rates placed JPEG/RBC in the top group of three algorithms among those submitted for possible inclusion as the next generation bandwidth compression(BWC) algorithm in the National Imagery Transmission Format Standard (NITFS). 1 INTRODUCTION Considerable research effort has been directed towards image compression in recent years. Tra-ditional image compression schemes are based on either scalar or block [3] (vector) encoding. Scalaralgorithms are generally simple to implement in hardware but only yield moderate levels of com-pression [4]. DPCM is an example of a scalar compression scheme in which the error signal cannot

Two stage residual lattice based vector quantization

Abstract: A two-stage image compression scheme is proposed. It is shown that, with this scheme considerable improvement can be achieved over standard JPEG. Two different schemes are presented. In the first scheme, each block is converted into DCT coefficients. The low frequency coefficients are quantized using a high rate lattice based vector quantizer (LVQ) in the first stage. In the second stage, the residue of this image is quantized with an LVQ. The results are comparable with that of the standard JPEG. In the second scheme, we use a standard JPEG, with a low bit rate, for the first stage and the residue of image is again quantized with an LVQ in the second stage. With this method the PSNR is improved by up to 4 dB in comparison to the standard JPEG at moderate bit rates. >