Fast Blind Quality Assessment of DIBRSynthesized Video based on High-High Wavelet Subband.

Free viewpoint video, as the development direction of the next-generation video technologies, uses the Depth-Image-Based Rendering (DIBR) technique for synthesis of video sequences at viewpoints where real captured videos are missing. As reference videos at multiple viewpoints are not available, a blind reliable real-time quality metric of synthesized video is needed. Although no-reference quality metrics dedicated to synthesized views successfully evaluate synthesized images, they are not that effective when evaluating synthesized video due to additional temporal flicker distortion typical only for video. In this paper, a new fast no-reference quality metric of synthesized video with synthesis distortions is proposed. It is guided by the fact that DIBR-synthesized images are characterized by increased high frequency content. The metric is designed under the assumption that the perceived quality of DIBR-synthesized video can be estimated by quantifying the selected areas in the high-high wavelet subband. The threshold is used to select the most important distortion sensitive regions. The proposed No-Reference Morphological Wavelet with Threshold (NRMWT) metric is computationally extremely efficient, comparable to PSNR, as the morphological wavelet transformation uses very short filters and only integer arithmetic. It is completely blind, without using machine learning techniques. Tested on the publicly available dataset of synthesized video sequences characterized by synthesis distortions, the metric achieves better performances and higher computational efficiency than the stateof the art metrics dedicated to DIBR-synthesized images and videos.