Enhancement method that provides direct and independent control of fundamental attributes of image quality for radiographic imagery

Image processing is used to transform raw digital radiographic image data, captured using CR (computed radiography) and DR (flat panel direct digital radiography) systems into a display-ready form. Ideally, an image-processing algorithm automatically renders an image for display, based on aims derived from observer performance studies. Establishing the rendering aim for different exam types, however, can be complex because the effects on image appearance introduced by the various steps in the rendering process are interdependent. This paper describes a new rendering algorithm that provides orthogonal control, to the first order, of five fundamental attributes of perceived image quality. These attributes are brightness, latitude, detail contrast, sharpness, and appearance of noise. The detail contrast and sharpness can be controlled in a density-dependent manner. The algorithm uses a multifrequency-band decomposition wherein the bands of the decomposition are manipulated, and the reconstructed image is passed through a tone-scale process that prepares the image for display. The rendering method is implemented in software on a workstation that enables interactive control of these image quality attributes in order to facilitate the determination of rendering aims for different exam types.