A mathematical theory of communication
TL;DR: This final installment of the paper considers the case where the signals or the messages or both are continuously variable, in contrast with the discrete nature assumed until now.
Abstract: In this final installment of the paper we consider the case where the signals or the messages or both are continuously variable, in contrast with the discrete nature assumed until now. To a considerable extent the continuous case can be obtained through a limiting process from the discrete case by dividing the continuum of messages and signals into a large but finite number of small regions and calculating the various parameters involved on a discrete basis. As the size of the regions is decreased these parameters in general approach as limits the proper values for the continuous case. There are, however, a few new effects that appear and also a general change of emphasis in the direction of specialization of the general results to particular cases.
Citations
More filters
TL;DR: Experimental and simulation results have demonstrated that the proposed system is secure, robust, and deters the risks of attacks for secure biometric image transmission.
41 citations
01 Jan 2008
TL;DR: For instance, this paper argued that the genetic code would be real only if it was associated with the production of meaning, but modern science does not deal with meaning and is bound therefore to relegate the genetic codes among the metaphorical entities.
Abstract: Semiotics is the study of signs and initially it was thought to be concerned only with the products of culture. Mental phenomena, however, exist also in animals, and cultural semiotics came to be regarded as a special case of biological semiotics, or biosemiotics, a science that started by studying semiotic phenomena in animals and then it was gradually extended to other living creatures. Eventually, the discovery of the genetic code suggested that the cell itself has a semiotic structure and the goal of biosemiotics became the idea that all living creatures are semiotic systems. This conclusion, however, is valid only if we accept that the genetic code is a real code, but an influential school of thought, known as physicalism, has apparently convinced many people that it is only a metaphor, a mere linguistic expression that we use in order to avoid long periphrases. The argument is that the genetic code would be real only if it was associated with the production of meaning, but modern science does not deal with meaning and is bound therefore to relegate the genetic code among the metaphorical entities.
41 citations
TL;DR: In this article, a Dynamic Data Exchange (DDE) link between a laser particle sizer (Malvern Mastersizer X) and a spreadsheet program (EXCEL for WINDOWS) was established to facilitate the acquisition and management of high quality grain-size data.
41 citations
TL;DR: Improvement in signal-to-noise ratio for the vector quantization approach in the hybrid coding is quite noticeable in image quality, particularly in reducing "blockiness" in the low bit rate encoded images.
Abstract: The transform and hybrid transform/DPCM methods of image coding are generalized to allow pyramid vector quantization of the transform coefficients. An asymptotic mean-squared error performance expression is derived for the pyramid vector quantizer and used to determine the optimum rate assignment for encoding the various transform coefficients. Coding simulations for two images at average rates of 0.5-1 bit/pixel demonstrate a 1-3 dB improvement in signal-to-noise ratio for the vector quantization approach in the hybrid coding, with more modest improvements in signal-to-noise ratio in the transform coding. However, this improvement is quite noticeable in image quality, particularly in reducing "blockiness" in the low bit rate encoded images.
41 citations
References
More filters
TL;DR: In this article, a quantitative measure of information is developed which is based on physical as contrasted with psychological considerations, and how the rate of transmission of this information over a system is limited by the distortion resulting from storage of energy is discussed from the transient viewpoint.
Abstract: A quantitative measure of “information” is developed which is based on physical as contrasted with psychological considerations. How the rate of transmission of this information over a system is limited by the distortion resulting from storage of energy is discussed from the transient viewpoint. The relation between the transient and steady state viewpoints is reviewed. It is shown that when the storage of energy is used to restrict the steady state transmission to a limited range of frequencies the amount of information that can be transmitted is proportional to the product of the width of the frequency-range by the time it is available. Several illustrations of the application of this principle to practical systems are included. In the case of picture transmission and television the spacial variation of intensity is analyzed by a steady state method analogous to that commonly used for variations with time.
1,741 citations
TL;DR: In this paper, it was shown that the wave shape depends somewhat on the type of circuit over which intelligence is to be transmitted and that for most cases the optimum wave is neither rectangular nor a half cycle sine wave as is frequently used but a wave of special form produced by sending a simple rectangular wave through a suitable network.
Abstract: This paper considers two fundamental factors entering into the maximum speed of transmission of intelligence by telegraph. These factors are signal shaping and choice of codes. The first is concerned with the best wave shape to be impressed on the transmitting medium so as to permit of greater speed without undue interference either in the circuit under consideration or in those adjacent, while the latter deals with the choice of codes which will permit of transmitting a maximum amount of intelligence with a given number of signal elements. It is shown that the wave shape depends somewhat on the type of circuit over which intelligence is to be transmitted and that for most cases the optimum wave is neither rectangular nor a half cycle sine wave as is frequently used but a wave of special form produced by sending a simple rectangular wave through a suitable network. The impedances usually associated with telegraph circuits are such as to produce a fair degree of signal shaping when a rectangular voltage wave is impressed. Consideration of the choice of codes show that while it is desirable to use those involving more than two current values, there are limitations which prevent a large number of current values being used. A table of comparisons shows the relative speed efficiencies of various codes proposed. It is shown that no advantages result from the use of a sine wave for telegraph transmission as proposed by Squier and others2 and that their arguments are based on erroneous assumptions.
459 citations