Objective measurement scheme for perceived picture quality degradation caused by MPEG encoding without any reference pictures The rapid progress in digital transmission technology has spurred demand for developing a technology that supports monitoring of video transmissions. Automating the picture quality assessment process is in particular demand because it currently depends on subjective assessments by human operators and places a heavy burden on them. The authors therefore propose an objective picture quality measurement method that works without reference pictures. In this proposed method, invisible markers are embedded into original pictures by use of the spread spectrum data hiding method. Since the markers are widely spread over the frequency domain, the degradation caused by MPEG compression can be estimated by detecting the extent of marker degradation. Our method is usable regardless of the kind of picture, bitrate, and number of stages of tandem codec connections. The degradation in picture quality caused by the embedded markers is quite small and not perceivable by the human eye. The proposed method is therefore applicable to a wide range of visual transmission services.

Linking Distortion Perception and Visual Saliency in H.264AVC Coded Video Containing Packet Loss In this paper, distortions caused by packet loss during video transmission are evaluated with respect to their perceived annoyance. In this respect, the impact of visual saliency on the level of annoyance is of particular interest, as regions and objects in a video frame are typically not of equal importance to the viewer. For this purpose, gaze patterns from a task free eye tracking experiment were utilised to identify salient regions in a number of videos. Packet loss was then introduced into the bit stream such as that the corresponding distortions appear either in a salient region or in a nonsalient region. A subjective experiment was then conducted in which human observers rated the annoyance of the distortions in the videos. The outcomes show a strong tendency that distortions in a salient region are indeed perceived as much more annoying as compared to distortions in the nonsalient region. The saliency of the distorted image content was further found to have a larger impact on the perceived annoyance as compared to the distortion duration. The findings of this work are considered to be of great use to improve prediction performance of video quality metrics in the context of transmission errors.