We have developed a region-based image processing method to enhance selective radiodense regions on digital radiographs. We employ a wavelet filtering technique to locate the radiodense regions-of-interest and then apply different degrees of enhancement procedure to them. The enhancement procedure is based on an unsharp masking technique controlled by a set of sigmoidal functions. The method was tested on computed chest radiographs to improve the visualization of the mediastinum and radiodense spine areas. The enhanced chest images showed improved visualization in the mediastinum area, and the visibility of vascular structures which were obscured by the diaphragm and mediastinum was improved. To demonstrate the method's potential in other medical image processing tasks, we applied it to cervical spine images. The processed cervical spine images also showed better visualization of the seventh cervical vertebrae and the first thoracic vertebrae in the high radiodense area caused by the superimposition of the patient's shoulder tissue over these regions of interest.