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Optical Engineering

The Use of a General Description of the Radiological Transmission Image for Categorizing Image Enhancement Procedures
Author(s): C. A. Mistretta
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Paper Abstract

The mathematical function describing the transmission of x-rays through an object depends on many geometrical and physical variables. A Taylor series expansion of the transmission function about an arbitrary point in the multivariable space displays the variety of terms which may be emphasized or isolated in order to accentuate certain information concerning the object under study. Conventional radiographic or fluoroscopic images are represented by the zero order term. This term can be used to derive higher order terms which depend explicitly on the spatial coordinates x and y, but contains only averaged or incomplete information about variables such as z (depth), E (energy), or t (time). One class of image enhancement procedures involves accentuation of whatever information is present on conventional radiographs by selective filtration of spatial frequency components or isolation of the x and y derivative terms. A second class of images with significantly different information content can be obtained by a priori use of knowledge about other variables in order to isolate other derivative terms. These images can be formed from linear combinations of zero order images associated with different values of the variable of interest. Examples of this class of images include tomography, time dependent subtraction, and absorption edge imaging. Because evaluations of "enhanced" images containing one subset of the possible image terms cannot be assumed to pertain to images containing other terms, it is suggested that the term "image enhancement" is too general and must be used with care.

Paper Details

Date Published: 1 April 1974
PDF: 5 pages
Opt. Eng. 13(2) 132134 doi: 10.1117/12.7971686
Published in: Optical Engineering Volume 13, Issue 2
Show Author Affiliations
C. A. Mistretta, University of Wisconsin (United States)

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