DEEI, University of Trieste, Via Valerio 10, Trieste, Italyarestrepo@units.it, marsi@units.it, ramponi@units.itKeywords: Tone mappings, gamma correction, unsharp masking, circular processing, color enhancement.Abstract: We present techniques for performing luminance mapping and unsharp-masking-like processing on digitalimages; they are specifically designed for their application on bounded and on circular signals. We studythe effect of gamma correction on contrast and develop an adaptive technique for luminance and contrastcorrection. We use the proposed tools for the enhancement of high contrast color images.