Showing papers on "Lossless compression published in 1970"

Compression of transmitted pulses in plasmas

Abstract: The compression of frequency-modulated RF pulses is discussed when the dispersive property of a lossless, isotropic, and homogeneous plasma is used to enhance the resolution of transmitted pulses at the receiver. Using the basic concept of group velocity, an expression is obtained for the carrier phase variation of a rectangular envelope pulse so that the pulse collapses on itself at the receiver. Unlike the chirp radar pulse, the frequency variation is not linear and the optimum detection of transmitted pulses depends on both the plasma frequency and the distance between the transmitter and the receiver. The method of convolution was used to obtain numerical results, which indicate that the formulation given results in compression for short propagation distances.

Noise margin and gain-bandwidth limitations of Legendre filters

Abstract: A general result on the relationship of noise margin and gain-bandwidth limitation of a singly terminated lossless equalizer is presented. This general result is applied to obtain the noise margin of the Legendre filters in a simple and straightforward manner.

The synthesis of a class of lossy distributed networks

Abstract: A class of filter networks that consists of sections of microstrip transmission lines employing a semiconductor dielectric operating between resistive terminations is investigated It is shown that the transfer functions of this class of lossy networks can be expressed in the same form as corresponding functions for lossless structures, thus making feasible the application of methods of synthesis already available for lossless structures A design procedure is presented for the systematic synthesis of this class of networks The procedure is illustrated by several design examples including both maximally flat magnitude and Chebyshev bandpass filters Two filters were fabricated using microstrip sections containing a high-loss silicon dielectric The measured and calculated responses of both filters were in good agreement

Color Image Transcoding of Lossless Encoder and Standard Lossy Decoder based on JP2K

Abstract: In JPEG2000 (JP2K) color image system, loss less coding signal is not able to be reconstructed with lossy decoder directly. Then, this report proposes a new transcoding between lossless encoder and standard lossy decoder for color image signals base on JP2K. A proposed encoder is required reversible color transform (RCT) and reversible discrete wavelet transform (RDWT) with compatibility to standard lossy decoder based on JP2K (JP2K lossy decoder). To improve the compatibility, proposed encoder is designed by using Non-scaled RCT and Non-Scaled RDWT with embedding scaling parameter into quantization header. Then, this method can be practical use with JP2K lossy decoder without any change. It also reduces total rounding error and lifting steps. The results show that proposed method can keep lossless coding performance and improve transcoding functionality to JP2K lossy decoder. The quality of transcoding image was achieved to 50.05 dB (PSNR).

On Information-Lossless Discrete-Time Systems

Abstract: The concept of lossless state or system is generalized by the definition of k-losslessness. If k>N( N-1)/2 for an N-state machine, k-lossless implies lossless. The series connection of a set of discrete time systems {Ai}, where Ai is ki-lossless, results in a system which is min{ki}-lossless. This result is a simple verification of the intuitive notion that a noiseless communication channel is only as lossless as the most lossy system in the channel. By means of input- output pair analysis, systems with the decomposition property (one of the necessary but not sufficient conditions for linearity) are shown to be information-lossless of finite order m, when one state has finite order m. Further, every state must have exactly the same order. For an N-state system with decomposition and zero-state linearity, information-lossless implies information-lossless of finite order m≤N. As a consequence, all information-lossless linear sequential machines used as encoders allow decoding to begin after m received symbols, provided that the encoder's starting state is known in advance.

Coding/decoding for data compression and error control on data links using digital computers

Abstract: Data compression and error control have, over the years, been treated as two separate disciplines. Data compression can substantially reduce the loading of communication channels and error control using coding methodology, can reduce the amount of errors in the messages being transmitted, or allow the system to operate with less power for a comparable uncoded information rate. This paper demonstrates that both functions can be combined into one operation by applying sequential decoding developed for error control to data compression. Because the same general method can be used to solve both problems, data compression and error control can be united in a single system and held accountable for the required theorems in information theory.

Entropy and data compression (Corresp.)

Abstract: An optimum compression ratio (OCR) is defined for a source, leading to "efficiency" of a compression algorithm and resulting in a good evaluation of data-compression schemes. Applications to first- and second-order Markov sources, in conjunction with the "fan" and "zero-order hold" compression schemes, are also presented.

Blind Scheme with Histogram Peak Estimation for Histogram Modication-Based Lossless Information Embedding

Abstract: In this paper, a simple scheme for histogram modification-based lossless information embedding (HM-LIE) is proposed. The proposed scheme is free from memorizing side information, i.e., blind. A HMLIE scheme modifies particular pixel values in an image in order to embed information in it on the basis of its histogram, i.e., tonal distribution. The scheme recovers the original image as well as extracts embedded information from a distorted image conveying embedded information. Most HM-LIE schemes should memorize a set of image-dependent side information per image. The proposed scheme does not have to memorize such information to avoid costly identification of the distorted image carrying embedded information because of the introduction of two mechanisms. One is estimating side information on the basis of a simple statistic, and the other is concealing not only main information but also a part of the side information in the image. These approaches make the proposed scheme superior to the conventional blind schemes in terms of the quality of images conveying embedded information.