The information spectrum as a measure of radiographic image quality and system performance

Abstract

The spectrum (spatial-frequency component) of the information capacity of a radiograph, which the authors call the information spectrum, is offered as a measure of image quality and system performance. The information spectrum is a much more practical expression than information capacity by itself: it combines synthetically the contract, the latitude, the sharpness and the granularity, and is expressed as a function of spatial frequency. The information spectrum can be readily calculated by using the dynamic density range and the MTF and noise Wiener spectrum at medium density range. A practical example is given. The appropriate system for each object can be selected by comparing the information spectral values of various imaging systems at the significant spatial frequency range predetermined for each object.