Dental radiographs are amenable to digital image processing and analysis for both subjective interpretation and quantification of scene features. Four general-purpose image processing programs for the Apple Macintosh II computer (NIH Image, Enhance, IP Lab and DIP Station) were applied to digital analysis of dental radiographs. These programs can manipulate and quantitatively analyse the gray scale and spatial data of dental images and improve their subjective quality. They can interactively make geometric measurements of features. The programs were evaluated for their versatility and applicability in the quantification of alveolar bone. Overall, NIH Image was judged most suitable for current dental imaging needs. Each of the other programs offered unique features that may be valuable in specific applications.