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In this work a new Reduced Reference (RR) Video Quality Metric (VQM) is proposed. The method takes advantage of the Human Visual System (HVS) sensitivity to sharp changes in the video. The proposed method has a spatial-temporal approach and because of that it is named as STAQ (Spatial-Temporal Assessment of Quality). In the first step of STAQ we take a temporal approach and find the matching regions...
ITU has standardized a computational model as Recommendation G.1070 for Quality of Experience (QoE) planning [1]. In our previous work, we proposed a system for calculating the G.1070 visual quality estimate in a monitoring scenario [2]. In G.1070, the visual quality is based, in part, on frame rate, bitrate, and packet-loss rate. For a fixed frame rate and a fixed packet-loss rate, the G.1070 visual...
Although Quality of Experience (QoE) plays a major role in the design and development of mobile applications and services, QoE assessment is still challenging, especially in real-life (so called ‘living lab’) contexts. This paper presents results from an exploratory, interdisciplinary study on QoE and more specifically, on the acceptability of varying audiovisual qualities during video watching on...
In video streaming applications, it is necessary to choose the rate of the encoded stream to match the available transmission channel capacity. To provide flexible means for rate adaptation, different scalable video coding schemes have been proposed. For example, if necessary the bitrate can be reduced either by downscaling the frame rate (temporal scalability) or the image quality (quality scalability)...
When evaluating the Quality of Experience (QoE) of audio conferences the participants talking behaviour is critical for their quality judgement. A dominant person, for instance, who talks and interacts a lot is likely to be more disturbed by conversation-related impairments than a less active person. Social interaction analysis provides reliable nonverbal audio features to predict dominance in face-to-face...
In this paper, we investigate whether the presence of audio with different quality levels can influence the outcome of subjective visual quality assessment in a Digital Cinema setting. We asked the participants to judge the visual quality when watching an audiovisual content in a Digital Cinema environment and investigated whether the participants can neglect the presence and the quality of audio...
The aim of this paper is to assess the impact of devices on Quality of Experience (QoE) of the user. As the types of video content viewed over handheld devices increases e.g. streaming video, it is important to evaluate the impact of the end device on video quality assessment. In this paper subjective tests were conducted with QCIF (176×144) videos over two devices — Personal Computer (PC) and mobile...
We propose an algorithm to detect salient regions for JPEG distorted images for two tasks: quality assessment and free viewing. The algorithm extracts low-level features such as contrast, luminance, quality and so on and uses a machine-learning framework to predict salient regions in JPEG distorted images. We demonstrate that the automatically predicted regions-of-interest highly correlate with those...
While traditional image quality metrics like MSE are mathematically well understood and tractable, they are known to correlate weakly to image distortion as observed by human observers. To address this situation, many full reference quality indices have been suggested over the years that correlate better to human perception, one of them being the well-known Structural Similarity Index by Wang and...
In multimedia quality assessment, observer ratings are typically averaged into mean opinion scores (MOS) to obtain a subjective ground truth for a set of stimuli. Valuable information about individual observer rating behaviour and inter-observer differences is lost that can be useful to improve subjective experiment procedures and quality of experience prediction models. In this paper, we present...
Efficient content-based access to large multimedia collections requires annotations that are human-meaningful, and user tagging of media is one means to obtain such semantic metadata. Tags can also act as user feedback essential for quality of multimedia experience assessment; however, tags can lack user context and become ambiguous between different users. Further, user tagging is a deliberate and...
The vergence-accommodation conflict, excessive screen disparity, binocular distortions and the motion component in stereoscopic videos are considered as main factors that may induce visual discomfort. In our previous study which was based on the experts-only experiment, we also found that the large relative disparity between the foreground and background and the fast planar motion were more likely...
Image quality scores collected in subjective experiments are widely used in image quality research, particularly in the design of objective quality assessment algorithms. It is therefore of vital importance to make sure that the collected scores reflect viewers' opinions in real-life situations. However, just by giving the viewers the task of assessing quality, there is a risk that their behavior...
This paper presents an experimental study on subjective quality of 3D video under packet loss conditions. A priority network is assumed, such that the base view of a stereoscopic video stream is delivered through a guaranteed channel and the auxiliary view is subject to packet losses over a low priority channel. Due to the packetisation scheme, one frame is lost whenever a packet is lost. Three frame...
In this paper, we identify quality dimensions which are relevant for speech communication services, such as mobile telephony or Voice-over-IP. These include dimensions perceived when listening to degraded speech, talking against echoes, double-talk capabilities, interacting with delay, conversing over channels with time-varying characteristics, and service-related dimensions experienced during speech...
Understanding bottom-up and top-down visual attention mechanisms related to visual quality perception can be greatly beneficial for the design of effective objective quality metrics. Subjective studies based on eye-movement tracking have been recently published that try to get more insight in these interactions. However, it is still not easy to find coherence across their results, also due to the...
One of the most interesting applications of single — sided Quality of Experience (QoE) metrics is their use in improving the quality of the service, as perceived by the user. This can be done either at the application level — by for example changing the encoding in use, or the level of error correction applied — or at the network level, for instance by choosing a different DiffServ marking strategy,...
This report tries to measure users' interest in images that appear on the screen by monitoring their attention via eye-tracking. Our Gaze Inference System analyzes the gaze-movement features to assign a user interest level (UIL) from 0 to 1 to every image that appears on the screen. Because the properties of the gaze features for every user are different from others, the framework is designed to be...
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