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Quality of Multimedia Experience, 2009. QoMEx 2009. International Workshop on

Date 29-31 July 2009

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Displaying Results 1 - 25 of 50
  • [Front cover]

    Publication Year: 2009 , Page(s): c1
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    Freely Available from IEEE
  • [Title page]

    Publication Year: 2009 , Page(s): i
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    Freely Available from IEEE
  • [Copyright notice]

    Publication Year: 2009 , Page(s): ii
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  • Welcome note

    Publication Year: 2009 , Page(s): iii - iv
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    Freely Available from IEEE
  • Organizing Committee

    Publication Year: 2009 , Page(s): v - vi
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    Freely Available from IEEE
  • Table of contents

    Publication Year: 2009 , Page(s): vii - x
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    Freely Available from IEEE
  • Impairment-factor-based audio-visual quality model for IPTV

    Publication Year: 2009 , Page(s): 1 - 6
    Cited by:  Papers (2)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (854 KB) |  | HTML iconHTML  

    This paper presents an audio-visual quality model for IPTV services. The model estimates the quality of high definition (HD, 1920times1080 pixels) audio-video as perceived by the user. It is developed for being applied to network planning and packet layer quality monitoring. Addressed degradations are mainly audio and video compression artifacts and packet loss. Results demonstrate a mutual influence of the perceived audio and video qualities, and the predominance of the video quality for the overall audio-visual quality. The model is based on impairment factors which express the quality impact of the different degradations. Those factors are computed from parameters extracted from the bit-stream or packet headers, such as audio and video bit-rates and packet-loss-rates, making the model computationally efficient. The model correlates at 97% with unknown subjective ratings. For comparison, we have developed a more classical audio-visual quality model based on audio and video qualities and their interaction, which shows lower performance than the impairment-based approach. Also provided is a comparison with models described in the the literature. View full abstract»

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  • A taxonomy of quality of service and Quality of Experience of multimodal human-machine interaction

    Publication Year: 2009 , Page(s): 7 - 12
    Cited by:  Papers (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (299 KB) |  | HTML iconHTML  

    Quality of Service (QoS) and Quality of Experience (QoE) are not only important for services transmitting multimedia data, but also for services involving multimodal human-machine interaction. In order to guide the assessment and evaluation of such services, we developed a taxonomy of the most relevant QoS and QoE aspects which result from multimodal human-machine interactions. It consists of three layers: (1) The QoS-influencing factors related to the user, the system, and the context of use; (2) the QoS interaction performance aspects describing user and system behavior and performance; and (3) the QoE aspects related to the quality perception and judgment processes taking place inside the user. For each of these layers, we provide metrics which make system evaluation more systematic and comparable. View full abstract»

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  • Influence of audio-visual attention on perceived quality of standard definition multimedia content

    Publication Year: 2009 , Page(s): 13 - 18
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (253 KB) |  | HTML iconHTML  

    When human subjects assess the quality of multimedia data, high level perceptual processes such as focus of attention (FoA) and eye movements are believed to play an important role in such tasks. While prior art reports incorporation of visual FoA into objective quality metrics, audio-visual FoA has been rarely addressed and utilized in spite of the importance and presence of both audio and video information in many multimedia systems. This paper explores the influence of audio-visual FoA in the perceived quality of standard definition audio-visual sequences. Results of a subjective quality assessment study are reported, where it is shown that the sound source attracts visual attention and thereby the visual degradation in the regions far from the source is less perceived when compared to sound-emitting regions. View full abstract»

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  • Evaluating a multimodal remote control: The interplay between user experience and usability

    Publication Year: 2009 , Page(s): 19 - 22
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (115 KB) |  | HTML iconHTML  

    This paper describes a study comparing two remote controls (unimodal vs. multimodal) for a TV and movie entertainment system. It was investigated if multimodality actually enhances a system's usability and improves its user experience. Additionally individual differences were taken into account (gender and age). The results show that multimodality improves user experience despite clear differences in usability. Furthermore it was shown that multimodal interfaces are actually providing universal access: The different user groups showed only slight differences when interacting with the multimodal remote control. View full abstract»

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  • Analysis of SSIM performance for Digital Cinema applications

    Publication Year: 2009 , Page(s): 23 - 28
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (506 KB) |  | HTML iconHTML  

    Visual quality is one of the most important issues in digital cinema applications, and the most practical method to measure visual quality is using objective metrics. Several objective metrics that take into account perceived visual quality have been developed in the past few years; one of them is based on the structural similarity paradigm. To analyze the performance of these objective metrics for digital cinema applications, a subjective visual quality assessment in digital cinema environments using contents from the digital cinema initiative (DCI) standard evaluation material has been conducted in a previous study. Since in practice digital cinema utilizes only high quality imagery, in this paper we analyze further a subset of high- quality stimuli from the previous study. View full abstract»

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  • Assessing the perceptual influence of H.264/SVC Signal-to-Noise Ratio and temporal scalability on full length movies

    Publication Year: 2009 , Page(s): 29 - 34
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (505 KB) |  | HTML iconHTML  

    The scalable video coding extension of the H.264/MPEG-4 AVC standard allows encoding a video sequence once and streaming it over heterogeneous networks to a variety of end devices. Different scalability techniques can be employed in order to deliver the most appropriate video bitstream based on network and device characteristics. However, users' Quality of Experience should be maximized at all time. In this paper, we investigate the influence of using temporal scalability and signal-to-noise ratio (quality) scalability on the Quality of Experience. A subjective test was conducted following a new methodology based on quality assessment using full length movies. This enables users to evaluate the video content in more realistic environments. During the test, subjects were asked to rate a movie which contained several scalability degradations. Results indicate that users, in general, favour temporal scalability over quality scalability. View full abstract»

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  • Modeling subjective tests of quality of experience with a Generalized Linear Model

    Publication Year: 2009 , Page(s): 35 - 40
    Cited by:  Papers (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (395 KB) |  | HTML iconHTML  

    Subjective tests of telecommunication services engaging a panel of subjects aim to analyze how service users experience their quality (QoE) with varying parameters of both a network and/or application itself. Subjects express their opinion on a few-grade categorical scale during tests performed in a controlled environment. The proposed Generalized Linear Model (GLZ)1 relates probabilities of particular QoE levels to independent network and application explanatory variables in a statistically credible way. The GLZ model is executed in several steps including maximum likelihood estimation of model parameters, selection of the most effective model with the Bayesian information criterion, model validation with a chi-squared test, and last but not least confidence interval estimation. Monitoring a QoE level with a GLZ model provides to operators an effective tool towards a mid- and long-term adaptation of both network and/or application parameters in order to follow users' experience and expectations. View full abstract»

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  • Subjective video quality as a function of bit rate frame rate, packet loss, and codec

    Publication Year: 2009 , Page(s): 41 - 46
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (303 KB) |  | HTML iconHTML  

    We present results regarding the impact on video quality of the factors: packet loss, bit rate, frame rate, and codec. The domain of this study is small-screen, mobile, low bit-rate video; the screen sizes covered are QCIF, CIF, and VGA. Bit rates are mainly in the range 64-1536 kb/s. Packet loss rates cover both typical wireline and wireless situations. The data on which this report is based come from a 15-lab study, the Multimedia Test by the Video Quality Experts Group. Forty-one separate experiments were conducted, each one using a different set of 166 specially-prepared video sequences, and each sequence being rated by a different set of 24 observers. The VQEG data can be analyzed to show the impacts of the factors packet loss, bit rate, frame rate, and codec. Our analysis consists of statistically relating the subjective judgments to these objective parameters. View full abstract»

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  • Measuring the perceived aesthetic quality of photographic images

    Publication Year: 2009 , Page(s): 47 - 52
    Cited by:  Papers (5)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1517 KB) |  | HTML iconHTML  

    There have been few studies that empirically assess the perception of aesthetics in photography. This study addressed a few image attributes that were hypothesized to be important to the perception of aesthetics. Thirty consumer photographers evaluated 450 images in a repeated measures factorial experiment and provided artistic quality ratings on a 0 to 100-point scale. The image set balanced main subject size, images with people and without people, and the type of perspective cue. Three first-party scenes supplied by each observer were evaluated by all observers in the study. Study results indicate that aesthetic preferences were mediated by all three of the study variables as a significant threeway interaction. Principal component and cluster analyses provided further insight into other features that impact aesthetic preference. Images in this study formed a continuum of quality ranging from low aesthetic and low technical quality to high aesthetic and high technical quality. View full abstract»

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  • On the mDCT-PSNR image quality index

    Publication Year: 2009 , Page(s): 53 - 58
    Cited by:  Patents (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1115 KB) |  | HTML iconHTML  

    Full reference image quality indices assign a quality index to a pair of an undistorted reference image and a distorted image to be assessed; the quality of the index itself is then defined by its ability to predict the outcome of subjective tests performed by human observers judging the quality of the same image pair. In this article, a new DCT based image quality index is introduced whose complexity is between that of algorithms like SSIM and complex, HVS-based algorithms like VDP. Detailed experiments on the LIVE database show that the proposed algorithm performs best close to or below the visual threshold, and outperforms there existing algorithms like SSIM or VDP requiring only a mediocre complexity. View full abstract»

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  • A grouplet-based reduced reference image quality assessment

    Publication Year: 2009 , Page(s): 59 - 63
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1180 KB) |  | HTML iconHTML  

    The past decades have witnessed the tremendous growth of digital image processing techniques for visual information representation and communication. Particularly, computational representation of perceived image quality has become a fundamental problem in computer vision and image processing. It is well known that the commonly used peak signal-to-noise ratio (PSNR), although analysis friendly, falls far short of this need. In this work, we propose a reduced reference (RR) perceptual image quality measure (IQM) based on the grouplet transform. Given a reference image and its "distorted" version, we first compute the grouplet transform in order to extract the information of textures and directions of both images. Then, contrast sensitivity function (CSF) filtering is performed to obtain same visual sensitivity information within both images. Thereafter, based on the properties of the human visual system (HVS), rational sensitivity thresholding is performed to obtain the sensitivity coefficients of both images. Finally, RR image quality assessment (IQA) is performed by comparing the sensitivity coefficients of both images. View full abstract»

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  • A no-reference sharpness metric sensitive to blur and noise

    Publication Year: 2009 , Page(s): 64 - 69
    Cited by:  Papers (22)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1119 KB) |  | HTML iconHTML  

    A no-reference objective sharpness metric detecting both blur and noise is proposed in this paper. This metric is based on the local gradients of the image and does not require any edge detection. Its value drops either when the test image becomes blurred or corrupted by random noise. It can be thought of as an indicator of the signal to noise ratio of the image. Experiments using synthetic, natural, and compressed images are presented to demonstrate the effectiveness and robustness of this metric. Its statistical properties are also provided. View full abstract»

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  • No-reference image blur assessment using multiscale gradient

    Publication Year: 2009 , Page(s): 70 - 74
    Cited by:  Papers (11)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (914 KB) |  | HTML iconHTML  

    The increasing number of demanding consumer video applications, as exemplified by cell phone and other low-cost digital cameras, has boosted interest in no-reference objective image and video quality assessment (QA). In this paper, we focus on no-reference image and video blur assessment. There already exist a number of no-reference blur metrics, but most are based on evaluating the widths of intensity edges, which may not reflect real image quality in many circumstances. Instead, we consider natural scenes statistics and adopt multi-resolution decomposition methods to extract reliable features for QA. First, a probabilistic support vector machine (SVM) is applied as a rough image quality evaluator; then the detail image is used to refine and form the final blur metric. The algorithm is tested on the LIVE Image Quality Database; the results show the algorithm has high correlation with human judgment in assessing blur distortion of images. View full abstract»

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  • No Reference Block Based Blur Detection

    Publication Year: 2009 , Page(s): 75 - 80
    Cited by:  Papers (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (357 KB) |  | HTML iconHTML  

    Blur is one of the most important features related to image quality. Accurately estimating the blur level of an image is of great help to estimate its quality. In this paper, a No Reference Block-based Blur Detection (NR-BBD) algorithm is proposed. It calculates the local blur at the boundaries of Macro Blocks (MBs) and then averages all of them to get the blur of the image. A content dependent weighting scheme is employed to reduce the influence from the texture. Compared with traditional edge based blur metrics, NR-BBD has a lower complexity, exhibits more stable for different image content, and results in a higher correlation with the perceived subjective visual quality (the resulting Pearson Correlation is 0.85 in the data set with 1176 images with different content type and different quality level.). View full abstract»

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  • Learning the properties of Receptive Fields in the context of Perceptual Image Quality assessment

    Publication Year: 2009 , Page(s): 81 - 86
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (169 KB) |  | HTML iconHTML  

    In this paper we introduce a statistical framework for image quality assessment based on the properties of hierarchical receptive fields (RFs) which are the primary mechanism for detection of visual patterns in the human visual system (HVS). We show how this frame work can be used to learn about different aspects of RFs such as the shape and size of RFs in the early vision and the directional preference of the RFs in the V1 cortex. The proposed framework offers a probabilistic approach to the detection of discrepancies (distortion) between a reference and a test visual stimuli (e.g. images). The proposed Probabilistic Perceptual Image Quality (PPIQ) framework offers a more realistic notion of image quality assessment, based on ldquocomparative memoryrdquo as opposed to ldquodifferential photographic memoryrdquo, which was required for explanation of many aspects of legacy image quality methods. View full abstract»

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  • A no-reference perceptual image sharpness metric based on a cumulative probability of blur detection

    Publication Year: 2009 , Page(s): 87 - 91
    Cited by:  Papers (15)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (343 KB) |  | HTML iconHTML  

    In this paper, a no-reference objective sharpness metric based on a cumulative probability of blur detection is proposed. The metric is evaluated by taking into account the human visual system (HVS) response to blur distortions. The perceptual significance of the metric is validated through subjective experiments. It is shown that the proposed metric results in a very good correlation with subjective scores especially for images with varying foreground and background perceived blur qualities. This is accomplished with a significantly lower computational complexity as compared to existing methods that take into account the visual attention information. View full abstract»

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  • Impact of router queuing disciplines on multimedia QoE in IPTV deployments

    Publication Year: 2009 , Page(s): 92 - 97
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1005 KB) |  | HTML iconHTML  

    Internet television (IPTV) is rapidly gaining popularity and is being widely deployed on the Internet. In order to deliver optimum user quality of experience (QoE), service providers need to understand and balance the trade-offs involved with user (video content, display device), application (codec type, encoding bit rate) and network (network health, router queuing discipline) factors that affect IPTV deployment. In this paper, we analyze the impact of router queuing disciplines, specifically packet-ordered and time-ordered first-in-first-out (FIFO) on the multimedia QoE performance. Our analysis is based on performance measurements of objective QoE metrics such as ldquoperceptible impairment raterdquo and ldquoframe packet lossrdquo in over 500 test scenarios in an IPTV testbed. Our salient analysis results include: (a) mapping of Good, Acceptable and Poor user QoE grades to network QoS levels, and (b) interplay of user and application factors in the mapped levels - under both PFIFO and TFIFO queuing disciplines. View full abstract»

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  • E-model supported switching between narrowband and wideband speech quality

    Publication Year: 2009 , Page(s): 98 - 103
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (226 KB) |  | HTML iconHTML  

    Forthcoming next generation networks (NGNs) introduce a new trend of integration into one all-IP platform. This process will decouple VoIP services from the network providers, introducing new service distribution aspects. VoIP devices will be enabled to seamlessly switch between wideband and narrowband speech operators and roam across diverse networks on demand, even during active calls. To design user-friendly speech quality switching posed by the NGNs, a reliable non-intrusive quality prediction model for quality monitoring will be required. Until now, none of the existing quality prediction models has been fully validated for use in NGNs. This prohibits quality prediction, when switching between wideband and narrowband speech codecs is necessary. In this paper, we validate the applicability of the e-Model for NGNs, targeting the situations when the speech bandwidth must be changed. We propose an additive codec switching impairment factor Iesw that improves the e-Model estimation for the new quality phenomenon. In this way, the achieved e-model correlation r = 0.93 enables VoIP quality monitoring of dynamic VoIP quality profiles, which is required to provide maximal user satisfaction in NGNs. View full abstract»

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  • Measuring mediated communication experience

    Publication Year: 2009 , Page(s): 104 - 109
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (345 KB) |  | HTML iconHTML  

    A great deal of our daily communication is technology-mediated and ranges from phone discussions to negotiations in sophisticated video conferences. We studied the mediated communication interaction and experience in three experimental setups: high quality video conferencing, Skype calls with webcam and audio conferencing. The communication experience was studied with a statistically developed five-dimensional measure. The differences were analysed with a direct multivariate discriminant analysis which enabled mapping of the set-ups in a two-dimensional communication experience space. The clearest difference between the groups was found in co-presence. The second dimension grounding also disclosed each groups' characteristics well. The added value of a multidimensional approach to user experience in communication technology is further discussed. View full abstract»

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