Color and Contrast Enhancement by Controlled Piecewise Affine Histogram Equalization

Abstract

This paper presents a simple contrast enhancement algorithm based on histogram equalization (HE). The proposed algorithm performs a piecewise affine transform of the intensity levels of a digital image such that the new cumulative distribution function will be approximately uniform (as with HE), but where the stretching of the range is locally controlled to avoid brutal noise enhancement. We call this algorithm Piecewise Affine Equalization (PAE). Several experiments show that, in general, the new algorithm improves HE results.