For some years the authors have been studying new irreversible compression techniques for angiocardiographic still images. They now present a new release of the software package named ITACA (Irreversible Threshold-bas...
详细信息
For some years the authors have been studying new irreversible compression techniques for angiocardiographic still images. They now present a new release of the software package named ITACA (Irreversible Threshold-based Angiocardiographic images Compressor and Archiver) collecting the irreversible compression techniques BEL, PABEL and PABCEL. In the authors' study they specially attended to the definition of a suitable path for image scanning. All compression algorithms the authors defined, permit one to check and to limit, for each pixel, the brightness and contrast errors committed in approximating the original image. algorithms do not request any preliminary training stage. The package was implemented using C language and runs on both MS-DOS and UNIX environments.< >
This paper describes a full-custom ASIC implementation of the QCELP voice compression algorithm. Applications for the ASIC are code division multiple access (CDMA) based cellular, personal-communications-networks (PCN...
详细信息
This paper describes a full-custom ASIC implementation of the QCELP voice compression algorithm. Applications for the ASIC are code division multiple access (CDMA) based cellular, personal-communications-networks (PCN), and wireless local loop. The ASIC contains a custom DSP core, utilizing internal RAM and ROM and a co-processor, which were optimized to perform QCELP and related voice-band processing. Key design concerns were power consumption, area, flexibility, and testability.< >
Presents a fractal image compression algorithm for inter/intra-frame video coding. The authors have shown previously how the iterated transformation theory (ITT) compression algorithm proposed by Jacquin (1993) can be...
详细信息
Presents a fractal image compression algorithm for inter/intra-frame video coding. The authors have shown previously how the iterated transformation theory (ITT) compression algorithm proposed by Jacquin (1993) can be modeled as the solution of a second kind two-scale functional equation. This approach allows one to introduce a chain of functional equations which one can use to build a pyramid algorithm for still image compression. The present authors use the prediction property of the ITT-chain to create a inter-frame video coder. They combine the inter-frame video encoder with the still-image ITT-pyramid to generate a hierarchy of bit streams that can be used in multimedia applications.< >
Presents a robust and implementable compression algorithm for multispectral imagery with selectable quality level within the near-lossless to visually lossy range. The three-dimensional terrain-adaptive transform-base...
详细信息
Presents a robust and implementable compression algorithm for multispectral imagery with selectable quality level within the near-lossless to visually lossy range. The three-dimensional terrain-adaptive transform-based algorithm involves a one dimensional Karhunen-Loeve transform (KLT) followed by two-dimensional discrete cosine transform (DCT). The images are spectrally decorrelated via the KLT to produce the eigen images. The resulting spectrally decorrelated eigen images are then compressed using the JPEG algorithm. The key feature of this approach is that it incorporates the best methods available to fully exploit the spectral and spatial correlation in the data. The novelty of this technique lies in its unique capability to adaptively vary the characteristics of the spectral decorrelation transformation based upon variations in the local terrain. The spectral and spatial modularity of the algorithm architecture allows the JPEG to be replaced by a totally different coder (e.g., DPCM). However. The significant practical advantage of this approach is that it is leveraged on the standard and highly developed JPEG compression technology. The algorithm is conveniently parameterized to accommodate reconstructed image fidelities ranging from near-lossless at about 5:1 compression ratio (CR) to visually lossy beginning at around 40:1 CR.< >
Occam filters are a class of filters for additive random noise, based on the idea that when a lossy data compression algorithm is applied to a noisy signal with the allowed loss set equal to the noise strength, the lo...
详细信息
Occam filters are a class of filters for additive random noise, based on the idea that when a lossy data compression algorithm is applied to a noisy signal with the allowed loss set equal to the noise strength, the loss and the noise tend to cancel rather than add. The authors apply non-linear Occam filters to broad-band signals. Using the chirp signal as a specific example, they find that the Occam filter outperforms the Wiener filter consistently.< >
Occam filters are a general technique for filtering random noise via data compression. Previously it was established that these filters converge in a learning theoretic sense, with convergence bounds that depended on ...
详细信息
Occam filters are a general technique for filtering random noise via data compression. Previously it was established that these filters converge in a learning theoretic sense, with convergence bounds that depended on the probability distribution of the noise variable. The paper presents a convergence bound for uniformly sampled signals that is independent of the probability distribution of the noise variable, barring some minimal assumptions. It also examines an application of Occam filters to remove random noise from digital video, thereby enabling improved nearly lossless compression.< >
The Consolidated Automated Support System (CASS) Automated Technical Information (ATI) System used to display Technical Manuals and Test Program Instructions is a page turner system. Each page of a manual is a raster ...
详细信息
The Consolidated Automated Support System (CASS) Automated Technical Information (ATI) System used to display Technical Manuals and Test Program Instructions is a page turner system. Each page of a manual is a raster page (bitmapped graphics) displayable at 72 dpi. Selection of these pages is accomplished by using ASCII index files. Expanding the content and use of the ASCII index files and linking the indexes causes the CASS ATI to appear to the user as a form of an IETM with less graphic files required. This approach will save development dollars and make the CASS ATI more user friendly. The addition of duplicate Computer Graphics Metafile (CGM) for each raster file makes the optical disk data used for CASS ATI totally updatable.< >
Text compression algorithms are normally defined in terms of a source alphabet Sigma of 8-bit ASCII codes. The authors consider choosing Sigma to be an alphabet whose symbols are the words of English or, in general, a...
详细信息
Text compression algorithms are normally defined in terms of a source alphabet Sigma of 8-bit ASCII codes. The authors consider choosing Sigma to be an alphabet whose symbols are the words of English or, in general, alternate maximal strings of alphanumeric characters and nonalphanumeric characters. The compression algorithm would be able to take advantage of longer-range correlations between words and thus achieve better compression. The large size of Sigma leads to some implementation problems, but these are overcome to construct word-based LZW, word-based adaptive Huffman, and word-based context modelling compression algorithms.< >
暂无评论