Extended summary form only given. Security mechanisms are discussed in the context of a cryptographic mechanism to ensure data integrity and to provide proof of origin, i.e. to guarantee that the data originates from ...
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Extended summary form only given. Security mechanisms are discussed in the context of a cryptographic mechanism to ensure data integrity and to provide proof of origin, i.e. to guarantee that the data originates from the 'true sender', using public-key (asymmetric) cryptosystems with the capability of digital signature. Because of possible attacks, the search for efficient and secure hash functions is an important open problem. Two methods are proposed, combining a hash function with compression algorithms.< >
Summary form only given. This paper describes an algorithm which provides a high degree of compression and at the same time allows logical Boolean operations to be performed directly on the compressed representation o...
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Summary form only given. This paper describes an algorithm which provides a high degree of compression and at the same time allows logical Boolean operations to be performed directly on the compressed representation of the index. An inverted index of English text using this technique has only 20% to 25% of the size of the original text. Since logical Boolean queries can be performed on the compressed index itself, access speed is greatly enhanced.< >
Summary form only given. The same logic design was implemented with a CMOS process in two ASIC technologies, gate array and standard cell. The noiseless compression algorithm and chip implementations were specific to ...
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Summary form only given. The same logic design was implemented with a CMOS process in two ASIC technologies, gate array and standard cell. The noiseless compression algorithm and chip implementations were specific to the requirements of the Earth Observing System High-Resolution Imaging Spectrometer (HIRIS) instrument.< >
This paper presents the picture codec engine (PCE), a single-chip still image compression/decompression processor that conforms to the proposed CCITT/ISO JPEG international standards. The PCD implements both sequentia...
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This paper presents the picture codec engine (PCE), a single-chip still image compression/decompression processor that conforms to the proposed CCITT/ISO JPEG international standards. The PCD implements both sequential and progressive modes of operation.
A study of a subband-based compression algorithm for still pictures is reported. A nonuniform band splitting is performed, then each subband signal is quantized by an adaptive vector quantizer with dynamic bit allocat...
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A study of a subband-based compression algorithm for still pictures is reported. A nonuniform band splitting is performed, then each subband signal is quantized by an adaptive vector quantizer with dynamic bit allocation. The output of each vector quantizer is processed by an arithmetic coder. Simulation results are reported, and it is shown that images of size 256*256 pixels with 265 gray levels can be encoded with excellent quality at rates between 0.5 and 1 bit/pixel and with good quality at rates below 0.3 bit pixel.< >
A data compression algorithm is proposed which automatically analyzes a collection of examples to identify the set of strings which would be most useful to encode them. There is considerable subtlety in identifying th...
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A data compression algorithm is proposed which automatically analyzes a collection of examples to identify the set of strings which would be most useful to encode them. There is considerable subtlety in identifying the most useful strings, since the problem is NP-complete, but analysis and encoding/decoding heuristics have been developed which construct excellent codes. This paper describes the algorithm and experimental results on four different special domains: mailing addresses, FORTRAN programs, weather radar images and UNIX manual pages.< >
A full duplex/multiplex security communication system with single radio carrier frequency is described. Totally different from traditional simplex or double-frequency-full-duplex radio techniques, this novel communica...
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A full duplex/multiplex security communication system with single radio carrier frequency is described. Totally different from traditional simplex or double-frequency-full-duplex radio techniques, this novel communication system utilizes time compression and expansion techniques and uses the idea of time slot allocation for multiplexing. By this scheme, full-duplex/multiplex communication system can be established on a single carrier frequency. With conventional radio techniques, it will be quite complicated to establish a full triplex or quadruplex communication system. With the proposed scheme, it is not difficult to implement this kind of system. The intrinsic security characteristic of this system is attractive. The signal compression algorithms provide various levels of security. Segmenting time slots and synchronizing signals provide another level of complexity.< >
Distortion-free compressibility of individual pictures by finite-state encoders is investigated. In a recent paper (see IEEE Trans. Inform. Theory, vol.32, no.1, p.1-8, 1986) the compressibility of a given picture I w...
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Distortion-free compressibility of individual pictures by finite-state encoders is investigated. In a recent paper (see IEEE Trans. Inform. Theory, vol.32, no.1, p.1-8, 1986) the compressibility of a given picture I was defined and shown to be the asymptotically attainable lower bound on the compression ratio that can be achieved for I by any finite-state encoder. Here, a different and more direct approach is taken to prove similar results, which are summarized in a converse-to-coding theorem and a constructive-coding-theorem that leads to a universal asymptotically optimal compression algorithm.< >
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