BiTA/SWCE: Image Enhancement With Bilateral Tone Adjustment and Saliency Weighted Contrast Enhancement

Researchers have proposed various image enhancement methods to make images better correlate to the human visual system. This letter proposed an innovative image enhancement framework that combines bilateral tone adjustment (BiTA) and saliency-weighted contrast enhancement (SWCE) methods. Unlike most curve-based global contrast enhancement methods, BiTA enhances the mid-tone regions that normally contain important scenes, in addition to the bright and dark regions. For local contrast enhancement, SWCE integrates the concept of image saliency into a simple filter-based contrast enhancement method. Regions with higher saliency values, which indicate that the regions have a higher extent of human interest, deserve a greater degree of enhancement. In addition, this letter presents the ratio of saliency-weighted relative entropy to noise to evaluate the enhancement quality. Simulation results show that the proposed schemes achieve high contrast enhancement with little noise and great image quality.