Showing papers on "Median filter published in 1975"

Picture processing and digital filtering

Abstract: Two-Dimensional transforms.- Two-dimensional nonrecursive filters.- Two-dimensional recursive filtering.- Image enhancement and restoration.- Noise considerations in digital image processing hardware.- Recent advances in picture processing and digital filtering.

Nonlinear filtering in coherent optical systems through halftone screen processes.

Abstract: Nonlinear filtering operations can be performed in coherent optical systems with the help of the halftone screen process. Theoretical and practical considerations regarding this type of system are presented. The use of these methods to achieve logarithmic filtering is emphasized. Applications to separation of multiplicative signals and noise, speckle noise reduction, and processing of radiographic images are considered. Experimental results are presented.

On the evaluation of roundoff noise in digital filters

Abstract: The usual method of measuring the roundoff noise generated in a digital filter may lead, at least in case of sign-magnitude truncation, to an excessive result due to incomplete cancellation of the useful output signal. A simple method for determining a corresponding corrective term is presented.

A Shortcoming of the Median Evoked Response

Abstract: A shortcoming of the Median Evoked Response is discussed and a means for dealing with it is suggested.

Random Noise Signal Processing

Abstract: Pulse echo flaw detection systems have found extensive use in industry for quality control of many types of metal and ceramic components. The random signal flaw detection system described in this paper provides an increase in sensitivity of several orders of magnitude compared to conventional pulse echo systems. Following a review of the theory of system operation, we present some recently obtained results of our system on materials which are strongly sound absorbing, including ceramics, plastics and metals as well as material s which have large grains. In addition to detecting flaws in strongly absorbing materials we feel that this system might also be utilized as a way of estimating grain size, inclusion size or porosity. Disciplines Materials Science and Engineering | Structures and Materials This 5. signal processing is available at Iowa State University Digital Repository: http://lib.dr.iastate.edu/cnde_yellowjackets_1975/8 RANDOM NOISE SIGNAL PROCESSING V. l. Newhouse, N. M. Bi l gutay and E. S. Furgason School of Electrical Engineering, Purdue University West lafayette, Indiana Pulse echo flaw detection systems have found extensive use in industry for quality control of many types of metal and cerami c components. The random si gnal flaw detection system described in this paper provides an increase in sensit ivity of severa l orders of magnitude compared to conventional pulse echo systems. Following a review of the theory of system operation, we present some recent ly obtained results of our system on materials which are st rongly sound absorbing, incl uding ceramics, plastics and metal s as well as material s which have large grains. In addition to detecting flaws in strongly absorbing materi als we feel that this system might also be utilized as a way of estimating grain size, inclusion size or porosity. Conventional pulse echo systems transmit a pulse and display the reflection from the target on an oscilloscope. To avoid problems of range ambiguity the time between pulses must be maintained long enough so that all the echoes are received before transmi tting another pul se. The range r esolution, the smallest distance by which the two targets can be separated for the system to resolve t hem, is proportional to the width of the transmitted burst . This in turn is inversely proportional to the bandwidth of the transmitted signal. As a result of t he above conditions, the on/off time of the transmitted s ignal is extremely small. The peak to average power ratio is proportional to the ratio of the range to the resoluti on, which is on the order of 1000. Therefore, conventional pulse echo systems may be cha racterized by the fol l owing equat ion: Maximum Range Range Resolution Burst Interval Burst Width Peak Power Average Power ( 1 ) This means that the pulse echo systems mus t put out power in bursts of great intensity , which may damage the transducer. The other great limitation of existing pul se echo systems is that they have no s ignal-to-noise ratio enhancement. Since the therma l noise power of ampli fie rs is proportional to their bandwidths , the signal-to-noi se ratio enhancement at the output of a sys tern is defined in the fo 11 O\~i ng \~ay