Region-based enhancement of digital chest radiographs

In routine chest radiographs, the mediastinum is often underexposed and vascular structures are obscured by the diaphragm. We have developed a region-based processing algorithm to enhance contrast and brightness of selected anatomical regions, such as the mediastinum, without altering the other regions. We employ wavelet processing technique to segment a chest radiograph into different gray level regions and then apply different degrees of contrast enhancement procedure to them. The image enhancement is controlled by a proposed sigmoid function. The enhanced images showed improved visualization in the mediastinum area over the original unprocessed chest radiographs. Furthermore, the visibility of vascular structures which are obscured by the diaphragm and mediastinum is improved