Enhancement of Dark Images in Presence of Optical Sources Using Iterative Homomorphic Filter (IHF)

Most of the conventional enhancement schemes although produce better enhancement performances in case of dark images, they mostly fail to enhance the images in existence of optical sources. The regions with high intensity are excessively amplified and saturated, resulting in the loss of original information. So, there is a requirement to effectively regulate the illumination and reflectance component for proper enhancement of an image under challenging illumination conditions. In order to achieve effective enhancement under such conditions, an “Iterative Homomorphic Filter” is proposed which is made adaptive depending on the image types. The proposed filter attenuates the illumination component and enhances the reflectance component iteratively depending upon the overall average instantly of an image. The homomorphic filter outputs after 1 ^st and pth iteration along with the original image are fused together to provide the enhanced output image which contains more information than the original. The experimental results display that the proposed technique shows improved enhancement efficiency for such images than most of the existing algorithms available in the literature in terms of subjective and objective measures.