A No-Reference Image Quality Measurement Approach for Mobile Video Calling Applications in Low Light Environment

The low light performance of mobile phone cameras has gained much improvement due to the rapid development of digital imaging technologies. Recently, many phone manufactures have advertised their remarkable night mode for taking photos in low light environment. At the same time, more and more mobile video applications are enhancing their low light performance. This work investigates image quality measurement for mobile video calling applications in low light environment. At first, a video database is constructed by capturing many videos under different lighting conditions. Then a no-reference quality measurement model, which contains spatial information, noise and motion blur metrics, is proposed and is fitted to human observers' mean opinion score (MOS). The experiment results show that this measurement method gives high correlation with subjective MOS. Using the proposed model, we can analyze how camera sensor parameters influence to image quality, which helps the development of more accurate exposure algorithms for video calling applications in low light environment.