Two HEVC encoder methods for block artifact reduction

The HEVC deblocking filter significantly improves the subjective quality of coded video sequences at lower bitrates. During the final phase of HEVC standardization, it was shown that the reference software encoder may produce visible block artifacts on some sequences with content that shows chaotic motion, such as water or fire. The paper analyses the reasons for blocking artifacts in such sequences and describes two simple encoder-side methods that improve the subjective quality on these sequences without degrading the quality on other content and without significant bitrate increase. The effect on subjective quality has been evaluated by a formal subjective test.