Showing papers on "JPEG 2000 published in 1993"

Rate-constrained picture-adaptive quantization for JPEG baseline coders

Abstract: A recursive algorithm is presented for generating quantization tables in JPEG (Joint Photographic Experts Group) baseline coders from the actual statistics of the input image. Starting from a quantization table with large step sizes, corresponding to low bit rate and high distortion, one entry of the quantization table is updated at a time so that, at each step, the ratio of decrease in distortion to increase in bit rate is approximately maximized. This procedure is repeated until a target bit rate is reached. Simulation results demonstrate that, with picture-adaptive quantization tables designed by the proposed algorithm, the JPEG DCT (discrete cosine transform) coder is able to compress images with better rate-distortion performance than that achievable with conventional empirically designed quantization tables. >

An evaluation of JPEG compression for on-line satellite images transmission

Abstract: Image compression is a key technology to realize on-line satellite image transmission economically and quickly Among various image compression algorithms, the JPEG algorithm is the international standard for still color image compression In this study, various kinds of satellite images were compressed with the JPEG algorithm The relation between compression ratio and image quality were evaluated As for the image quality evaluation, both subjective evaluation and objective evaluation were performed It was determined that all the test satellite images could be compressed to at least 1/10 of the original data volume preserving high visual image quality The degradation of spatial distribution quality of the compressed images were evaluated using power spectrum of original and compressed images >

Medical Image Compression Using JPEG Progressive Coding

Abstract: The international standard for digital compression and coding of continuous-tone still images known as JPEG(Joint Photographic Experts Groups) standard is implemented and tested for medical image archiving and communication For a series of head sections of magnetic resonance images, compression ratio of about 10 is obtained without noticeable image degradation Compared to existing full-frame bit-allocation technique, the JPEG standard achieves higher compression with higher signal-tc-noise ratio The reconstructed images by the JPEG standard slao show much less Gibb’s artifact Feature of the progressive image build-up of the JPEG progressive coding appears useful in medical image archiving and communication where fast search of image from huge image data base and urgent diagnosis from remote site are often in need

Color Space Selection for JPEG Image Compression.

Abstract: The Joint Photographic Experts Group's image compression algorithm has been shown to provide a very efficient and powerful method of compressing images. However, there is little substantive information about which color space should be utilized when implementing the JPEG algorithm. Currently, the JPEG algorithm is set up for use with any three-component color space. The objective of this research is to determine whether or not the color space selected will significantly improve the image compression. The RGB, XYZ, YIQ, CIELAB, CIELUV, and CIELAB LCh color spaces were examined and compared. Both numerical measures and psycho-physical techniques were used to assess the results. The final resuLts indicate that the device space, RGB, is the worst color space to compress images. In comparison, the nonlinear transforms of the device space, CIELAB and CIELUV, are the best color spaces to compress images. The XYZ, YIQ, and CIELAB LCh color spaces resulted in intermediate levels of compression.

Fast Discrete Cosine Transform Approximation for JPEG Image Compression

Abstract: The discrete cosine transform (DCT) is widely applied in various fields including image data compression and was chosen as a basis of International JPEG (Joint Photographic Experts Group) Still Image Compression Standard. All known DCT implementations are sufficiently complicated, because the multiplication operations are making use of. This paper presents a new computational scheme for JPEG baseline system implementation in which the register shifts and additions are used only.

A comparative study of JPEG and residual VQ compression of radar imagery

Abstract: The Joint Photographic Expert Group (JPEG) compression standard and a type of vector quantization called residual vector quantization (RVQ) are evaluated for the real-time compression of precision approach radar (PAR) video data. Experimental results obtained from simulated PAR imagery are presented which allow a performance and complexity comparison of the two compression methods. For low to moderate compression ratios, JPEG is the preferable solution because of its good performance and relatively low complexity. For higher compression ratios, JPEG gives unacceptable image quality and RVQ is the preferred solution. >

Applications of the JPEG standard in a medical environment

Abstract: JPEG is a very versatile image coding and compression standard for single images. Medical images make a higher demand on image quality and precision than the usual 'pretty pictures'. In this paper the potential applications of the various JPEG coding modes in a medical environment are evaluated. Due to legal reasons the lossless modes are especially interesting. The spatial modes are equally important because medical data may well exceed the maximum of 12 bit precision allowed for the DCT modes. The performance of the spatial predictors is investigated. From the users point of view the progressive modes, which provide a fast but coarse approximation of the final image, reduce the subjective time one has to wait for it, so they also reduce the user's frustration. Even the lossy modes will find some applications, but they have to be handled with care, because repeated lossy coding and decoding leads to a degradation of the image quality. The amount of this degradation is investigated. The JPEG standard alone is not sufficient for a PACS because it does not store enough additional data such as creation data or details of the imaging modality. Therefore it will be an imbedded coding format in standards like TIFF or ACR/NEMA. It is concluded that the JPEG standard is versatile enough to match the requirements of the medical community.© (1993) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Image quality improvement by pre- and post-processing in DCT coding

Abstract: Coding for full-color still-image is standardized internationally by JPEG (Joint Photographic Experts Group). The coding method is used in wide area applications. In many cases, continuous-tone images are accompanied by characters. So improvements of JPEG coding by pre and post processing are investigated in mixed images. In this process, we use sharpening before JPEG coding as a pre-processing, and we use smoothing after JPEG coding as a post- processing. In both pre and post processing, the degree of emphasis is controlled by a weighting factor and the quality is compared between processed and unprocessed images. As a result of this process, it is confirmed that the processed image is better than an unprocessed image in quality.© (1993) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

High-performance JPEG image compression chip set for multimedia applications

Abstract: By its very nature, multimedia includes images, text and audio stored in digital format. Image compression is an enabling technology essential to overcoming two bottlenecks: cost of storage and bus speed limitation. Storing 10 seconds of high resolution RGB (640 X 480) motion video (30 frames/sec) requires 277 MBytes and a bus speed of 28 MBytes/sec (which cannot be handled by a standard bus). With high quality JPEG baseline compression the storage and bus requirements are reduced to 12 MBytes of storage and a bus speed of 1.2 MBytes/sec. Moreover, since consumer video and photography products (e.g., digital still video cameras, camcorders, TV) will increasingly use digital (and therefore compressed) images because of quality, accessibility, and the ease of adding features, compressed images may become the bridge between the multimedia computer and consumer products. The image compression challenge can be met by implementing the discrete cosine transform (DCT)-based image compression algorithm defined by the JPEG baseline standard. Using the JPEG baseline algorithm, an image can be compressed by a factor of about 24:1 without noticeable degradation in image quality. Because motion video is compressed frame by frame (or field by field), system cost is minimized (no frame or field memories and interframe operations are required) and each frame can be edited independently. Since JPEG is an international standard, the compressed files generated by this solution can be readily interchanged with other users and processed by standard software packages. This paper describes a multimedia image compression board utilizing Zoran's 040 JPEG Image Compression chip set. The board includes digitization, video decoding and compression. While the original video is sent to the display (`video in a window'), it is also compressed and transferred to the computer bus for storage. During playback, the system receives the compressed sequence from the bus and displays it on the screen.

Optimizing JPEG quantization matrices for different applications

Abstract: JPEG has already found wide acceptance for still frame image compression. The quantization matrices (QMs) play a critical role in the performance of the JPEG algorithm but there has been a lack of effective QM design tools. As a result, sub-optimal QMs have commonly been used and JPEG has been judged to be inappropriate for some applications. It is our contention that JPEG is even more widely applicable than `common knowledge' would admit. This paper describes a low-cost design tool that has been developed and is currently being successfully applied to design QMs for various sensors including IR, SAR, medical, scanned maps, and fingerprints.© (1993) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.