Automatic Color Enhancement (ACE) and its Fast Implementation

Automatic Color Enhancement "ACE" is an effective method for color image enhancement introduced by Gatta, Rizzi, and Marini based on modeling several low level mechanisms of the human visual system. The direct computation of ACE on an NxN image costs O(N4) operations. This article describes two fast approximations of ACE. First, the algorithm of Bertalmío, Caselles, Provenzi, and Rizzi uses a polynomial approximation of the slope function to decomposes the main computation into convolutions, reducing the cost to O(N2 log N). Second, an algorithm based on interpolating intensity levels also reduces the main computation to convolutions. The use of ACE for image enhancement and color correction is demonstrated