Automatic anatomically selective image enhancement in digital chest radiography.

A technique for automatic anatomically selective enhancement of digital chest radiographs is developed. Anatomically selective enhancement is motivated by the desire to simultaneously meet the different enhancement requirements of the lung field and the mediastinum. A recent peak detection algorithm and a set of rules are applied to the image histogram to determine automatically a gray-level threshold between the lung field and mediastinum. The gray-level threshold facilitates anatomically selective gray-scale modification and/or unsharp masking. Further, in an attempt to suppress possible white-band or black-band artifacts due to unsharp masking at sharp edges, local contrast adaptively is incorporated into anatomically selective unsharp masking by designing an anatomy-selective emphasis parameter which varies asymmetrically with positive and negative values of the local image contrast.