Color image enhancement by three-dimensional histogram modification

Abstract

Histogram-based color image enhancement is usually accomplished by transforming from RGB coordinates to another coordinate system, modifying the components represented in that system, and converting the results back to RGB. Although a few methods function directly in RGB space, they also attempt to reduce dimensonality from the histogram's original three dimensions. Such methods seldom yield images that use the full extent of RGB color range. A new method called "histogram explosion" has been developed to perform true multivariate enhancement directly in RGB color space. Discussed are the algorithm's operational parameters, behavior, implementation, and possible improvements. Results show histogram explosion to be very effective and flexible in enhancing color images. Finally, two iterative methods are suggested as possible approaches for the extension of the histogram equalization algorithm to operate upon three dimensional histograms.