An Adaptive Image Enhancement Method Based on Contourlet Transform and Improved Ant Colony Algorithm

摘要

To overcome the problems of losing detail geometric information of images and tending to amplify noise, which exist in traditional image enhancement methods, an adaptive image enhancement method based on Contourlet transform and improved ant colony algorithm is proposed. Firstly, we obtain the coefficients in different scales and different directions by image decomposition using the Contourlet transform. Then, we adopt an adaptive enhancement function with the ability of both feature enhancement and noise reduction to modify the Contourlet coefficients nonlinearly, and use an improved ant colony algorithm to adaptively adjust the parameters of the enhancement function. To find the optimal parameters, a novel evaluation criterion for image enhancement is introduced. Finally, we obtain the enhanced image by Contourlet inverse transform. The experimental results show that our method obtains significant performance in feature enhancement with low contrast and noise reduction over the wavelet-based and Contourlet-based non-adaptive image enhancement methods.