Objective video quality metrics are designed to be as reliable as the subjective quality assessments on which they are calibrated and validated. However, existing standard methodologies for subjective video quality assessment provide low reliable results for some conditions. We investigate whether an extension of the quality ruler experimental methodology, originally defined for images and shown to be more reliable than, e.g., standard single stimulus (SS) methods, can be adapted to reliably assess the quality of videos. The video quality ruler methodology allows subjects to assess video quality using a set of reference anchor images (the ruler), spanning a wide range of quality altogether, but closely spaced in function of quality one from the other. Subjects are asked to compare the quality of the displayed test video with the quality of these anchor images, displayed on a tablet, and indicate which of the reference images matches in quality the test video. As a result, the video quality assessment task is reduced to a set of visual comparisons between video and reference image quality. We describe how to adapt the original quality ruler methodology to video quality assessment, and we compare the proposed methodology with two other, widely used experimental methodologies: the single stimulus (SS) and the double stimulus (DS) method. Our results show that video quality ruler is a reliable method to assess video quality according to a multitude of criteria.
We report the results of a set of psychophysical experiments that measure the perceptual strengths of videos with different combinations of blockiness, blurriness, and packet-loss artifacts. Participants were instructed to search each video for impairments and rate the strength of their individual features (artifacts). A repeated-measure analysis of variance (RM-ANOVA) performed on the data showed that artifact physical strengths have a significant effect on annoyance judgments. We tested a weighted Minkowski model, a support vector regression model, and a linear model on the experimental data. We found that all these models give a good description of the relation between individual artifact perceptual strengths and the overall annoyance. In the other words, all models presented a very good correlation with the experimental data, showing that annoyance can be modeled as a multidimensional function of the individual artifact perceptual strengths. Additionally, results show that there are interactions among artifact signals.
KEYWORDS: Video, Visualization, Micro unmanned aerial vehicles, Video compression, Image quality, Eye, Image compression, Video processing, Video coding, Data processing
In digital video systems, impairments introduced during the capture, coding/decoding processes, delivery and display might reduce the perceived quality of the visual content. Recent developments in the area of visual quality have focused on trying to incorporate aspects of gaze patterns into the design of visual quality metrics, mostly using the assumption that visual distortions appearing in less salient areas might be less visible and, therefore, less annoying. Most of these studies, however, have considered the presence of a single artifact (e.g. blockiness or blur) impairing the image. In practice, this is not the case, as multiple artifacts may overlap, and their combined appearance may be strong enough to deviate saliency from its natural pattern. In this work, our focus is on measuring the impact and the influence of combinations of artifacts on the video saliency. For this purpose, we tracked eye-movements of participants in a subjective quality assessment experiment during a free-viewing and a quality assessment tasks. Results show that the gaze locations change from pristine videos to impaired videos. These changes seem to be more related to the quality level and content of videos than to the specific combination of artifacts.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.