Proper contrast change can improve the perceptual quality of most images, but it has largely been overlooked in this paper of image quality assessment (IQA). To fill this void, we, in this paper, first report a new large dedicated contrast-changed image database (CCID2014), which includes 655images and associated subjective ratings recorded from 22 inexperienced observers. We, then, present a novel reduced-reference image quality metric for contrast change (RIQMC) using phase congruency and statistics information of the image histogram.
Validation of the proposed model is conducted on contrast related CCID2014, TID2008, categorical image quality (CSIQ), and TID2013 databases, and results justify the superiority and efficiency of RIQMC over a majority of classical and state-of-the-art IQA methods. Furthermore, we combine aforesaid subjective and objective assessments to derive the RIQMC-based optimal histogram mapping (ROHIM) for automatic contrast enhancement, which is shown to outperform recently developed enhancement technologies.