For films produced by digital imaging modalities such as CR, CT, and MR, non-linear pixel value look-up tables can be used to present images in a format that is well matched to human visual perception. The use of nonlinear look-up tables typically allows selected elements of dynamic range to be emphasized or de-emphasized within the constraints of the film characteristics. The resulting films may contain more diagnostic information than is achievable using linear look-up tables, thus allowing assessment of individual image features within the overall image context, often without the need for localized adjustment of contrast. Similar benefits may be achievable for softcopy display of digital images from digital modalities such as CT, MR and digital fluoroscopy as well as CR, digitized analog films and mammography images through the implementation of non-linear look-up tables for softcopy image display. A research project based upon the implementation of non-linear display functions within diagnostic-quality PACS workstations is described. A modular, open-architecture application has been implemented to facilitate development and clinical assessment of non-linear display functions and fifteen `standard' non-linear display functions for CR images have thus far been implemented and imbedded into a UNIX-based PACS workstation by means of this application. In addition, a monitor compensation function has been developed to more closely match the characteristics of softcopy image display to those of film. A data histogram feature has also been implemented and a user interface developed to allow viewing of histograms as well as interactive modification of tonal transfer function parameters. The scope of this project also included a preliminary assessment of the diagnostic improvements to radiologic workstations that employ these capabilities.