Digitized longitudinal tomography.

An analog video longitudinal tomographic system has been converted to a digital format that reconstructs the tomographic section through the use of matrixes representing the gray scale values of the analog-recorded video images. This was done so that some simple preprocessing could be used to eliminate electronic noise and thereby increase the effective signal to noise ratio. Signal to noise was also increased by the elimination of the analog image displacement circuits (ramp generators). In addition to an improvement in the diagnostic quality (gray scale) of anatomic images, a capability to image contrast differentials as low as 1% has been achieved. A display system provides the ability to use windows having both variable central levels and widths.