Local Gamma Correction using Bi-linear Function for Dark Image Enhancement

Enhancement of dark images with embedded light sources still remains a challenging task. The classical methods are effective in enhancing the dark regions of an image but results in over enhancement of the bright regions. The over enhancement leads to the loss of original information and degradation of image quality. To effectively enhance the dark and bright regions of an image, a Bi-linear piecewise gamma correction method is proposed here. The proposed method employs two linear functions for simultaneous enhancement of dark and bright regions. The Bi-linear piecewise mapping function is used for the estimation of local gamma factor as per the local mean intensity so as to enhance different local intensity regions effectively. Experimental results show that the proposed method works better than many of the existing enhancement techniques in terms of objective and subjective measures.