A level crossing enhancement scheme for chest radiograph images.

A new approach for contrast enhancement of chest radiograph image data is presented. Existing methods for image enhancement focus mainly on the properties of the image to be processed while excluding any consideration of the observer characteristics. In several applications, particularly in the medical imaging area, effective contrast enhancement for diagnostic purposes can be achieved by including certain basic human visual properties. In this paper we shall present a novel (recursive) algorithm that tailors the required amount of contrast enhancement based on a combination of the optimal phase representation and the theory of projection onto a convex set. Constraints of maximum bandwidth of the image data, appropriate knowledge of the amplitude value of the image data, heuristic limitations and level crossing measurements serve to impose additional information. So that, the enhanced image data may better converge to the good quality image.