A low-complexity metric for the estimation of perceived chrominance sub-sampling errors in screen content images

摘要

In web conferencing and remote desktop applications screen sharing is a popular feature. Due to the limited data rate, image and video compression technologies are used to enable this functionality over the internet. However, the commonly used basic profiles of modern video codecs typically utilize the YCbCr color space involving 4:2:0 chrominance sub-sampling. This sub-sampling introduces visually disturbing artifacts for screen content, which may be avoided or reduced if they could be automatically detected. However, these artifacts are shown to be hardly captured by conventional image quality metrics. To address this problem, we developed the Perceived Chrominance Sub-sampling Error (PCSE) metric. Moreover, we created a subjectively evaluated screen content image data set, which is employed for the performance evaluation. The PCSE achieves absolute correlation coefficient values of almost 0.8. Thus, conventional quality metrics are significantly outperformed.