Evidence is reviewed suggesting that a Laplacian probability density function constitutes a more valid model for high-pass filtered imagery than the Gaussian model postulated in earlier work. In addition, it is shown that this discrepancy does not either seriously weaken the applicability of this class of images to a major image restoration method or challenge any other basic conclusions of the previous work.

A terminal/time share system for operator interactive left ventricular volume estimation is described. The system concept could provide a cost effective alternative to comparable minicomputer based methods and a potential for software resource sharing among several geographically remote users.

The advent of increased government involvement in occupational health maintenance with compensation for affected individuals is requiring new approaches to medical decision making. One aspect of this involvement will perhaps include the automatic mass diagnostic screening of medical films for the detection of a specffic abnormality with an occupational etiology. The results of two complementary approaches for performing diagnostic screening for presence and profusion of coal worker's pneumoconiosis from the routine posterior-anterior chest radiograph are presented. The first is a digital approach utilizing the measurement of image texture, while the second uses hybrid optical-digital methods involving the optical Fourier tramsform. Both approaches yielded classification results comparable to experienced radiologists.

Feature extraction is one of the more difficult steps in image pattern recognition. Some sources of difficulty are the presence of irrelevant information and the relativity of a feature set to a particular application. Several preprocessing techniques for enhancing selected features and removing irrelevant data are described and compared. The techniques include gray level distribution linearization, digital spatial filtering, contrast enhancement, and image subtraction. Also, several feature extraction techniques are illustrated. The techniques are divided into spatial and Fourier domain operations. The spatial domain operations of directional signatures and contour tracing are first described. Then, the Fourier domain techniques of frequency signatures and template matching are illustrated. Finally, a practical image pattern recognition problem is solved using some of the described techniques.