Showing papers on "Lossless compression published in 1978"

Selection of prefix and postfix word fragments for data compression

Abstract: In this paper a simple algorithm is used for selection of a set of codeable substrings that occur at the front or rear of the words in a textual data base Since the words are assumed to be non-repeating, the technique is useful for data compression of dictionaries The time complexity of the algorithm is governed by the associated sorting algorithm and hence is 0 ( n log n ) It has been applied to three sample data bases, consisting of words selected from street names, authors names, or general written English text The results show that the substrings at the rear of the words, yield better compression than those at the front By application of results of an earlier study in compression coding, efficient encoding and decoding procedures are presented for use in on-line transmission of data

On lossless bandpass ladder networks

Abstract: An algorithm for determining the B continued fraction and, hence, the values of elements of a lossless bandpass (band-elimination) ladder network from its state space description is presented.

Fixed-Error Encoding For Bandwidth Compression

Abstract: We present a DPCM technique that uses a fixed-error approach to minimize the loss of information in compression of a picture. The technique uses an initial N-bit quantization of the image and zero-error encoding of the difference signal. It produces no slope overload and a compression ratio of about 4 to 1. We compare the technique to three other encoding schemes, including a new, "one-pass", cosine transform encoder.© (1978) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Two-dimensional speech compression

Abstract: The application of recent video data compression techniques to speech data is described. In order to effectively apply these techniques, the speech data should be segmented so as to achieve a high degree of correlation between corresponding samples in adjacent speech segments, allowing the formation of a two-dimensional speech "raster" with significant correlation in both dimensions. Several methods for generating such two-dimensional formats are proposed, and the results of applying the hybrid cosine-transform/DPCM compression algorithm [1] and the two-dimensional cosine transform to selected data formats are presented. Also proposed are several hardware configurations for the possible application of these results to narrowband speech processing.