Enhancement of Video Imagery by Modified Intensity-Dependent Spatial Summation

摘要

A contract-enhancement algorithm is described which avoids the flat noisyappearance often produced by histogram equalization. This algorithm is based on the intensity-dependent spatial summation (IDS) model purported by Cornsweet and Yellott. The model's initial intent was to demonstrate its ability to replicate certain effects in human vision. Its implementation as an image-enhancement routine has predominantly emphasized its ability to enhance edges in imagery. The model has been modified to produce enhancement not only at edges but throughout the entire image profile. As a comparison to histogram equalization, which collapses some quantilization levels in the process of expanding others, the algorithm largely preserves the original brightness gradations as it expands them. Thus, the shape-from-shading cues so important to the perception of form and contour are preserved. Also, this technique, in most cases, enhance high frequency noise to a far lesser extent than does histogram equalization.