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Prof. Dr. Marcus Barkowsky

Forschung:

  • Quality of Experience
  • Algorithmen für Videoqualitätsanalyse
  • Modellierung des menschlichen visuellen Systems
  • Durchführung und Auswertung perzeptiver Vergleichsstudien
  • Perzeptive Verfahren in der Videocodierung

Lehre:

  • Interaktion
  • Internet of Things, Netzwerke und Mikroprozessoren
  • Digitale Signalverarbeitung
  • Informatik, insb. Software Engineering

Fakultät Angewandte Informatik

Professor:innen

Professor

Studiengangskoordinator “Interaktive Systeme und Internet of Things”

DEGG's 2.17

0991/3615-409

Sprechzeiten

Donnerstag, 15:15-15:45 nach Email-Vereinbarung

Sortierung:
Zeitschriftenartikel

  • L. Tiotsop
  • T. Mizdos
  • Marcus Barkowsky
  • P. Pocta
  • A. Servetti
  • E. Masala

Mimicking Individual Media Quality Perception with Neural Network based Artificial Observers

In: ACM Transactions on Multimedia Computing, Communications, and Applications vol. 18 pg. 1-25.

  • (2022)

DOI: 10.1145/3464393

Abstract anzeigen

The media quality assessment research community has traditionally been focusing on developing objective algorithms to predict the result of a typical subjective experiment in terms of Mean Opinion Score (MOS) value. However, the MOS, being a single value, is insufficient to model the complexity and diversity of human opinions encountered in an actual subjective experiment. In this work we propose a complementary approach for objective media quality assessment that attempts to more closely model what happens in a subjective experiment in terms of single observers and, at the same time, we perform a qualitative analysis of the proposed approach while highlighting its suitability. More precisely, we propose to model, using neural networks (NNs), the way single observers perceive media quality. Once trained, these NNs, one for each observer, are expected to mimic the corresponding observer in terms of quality perception. Then, similarly to a subjective experiment, such NNs can be used to simulate the users’ single opinions, which can be later aggregated by means of different statistical indicators such as average, standard deviation, quantiles, etc. Unlike previous approaches that consider subjective experiments as a black box providing reliable ground truth data for training, the proposed approach is able to consider human factors by analyzing and weighting individual observers. Such a model may therefore implicitly account for users’ expectations and tendencies, that have been shown in many studies to significantly correlate with visual quality perception. Furthermore, our proposal also introduces and investigates an index measuring how much inconsistency there would be if an observer was asked to rate many times the same stimulus. Simulation experiments conducted on several datasets demonstrate that the proposed approach can be effectively implemented in practice and thus yielding a more complete objective assessment of end users’ quality of experience.
  • Angewandte Informatik
  • DIGITAL
Beitrag (Sammelband oder Tagungsband)

  • L. Tiotsop
  • T. Mizdos
  • E. Masala
  • Marcus Barkowsky
  • P. Pocta

How to Train No Reference Video Quality Measures for New Coding Standards using Existing Annotated Datasets?

pg. 1-6.

  • (2021)

DOI: 10.1109/MMSP53017.2021.9733456

Abstract anzeigen

Subjective experiments are important for developing objective Video Quality Measures (VQMs). However, they are time-consuming and resource-demanding. In this context, being able to reuse existing subjective data on previous video coding standards to train models capable of predicting the perceptual quality of video content processed with newer codecs acquires significant importance. This paper investigates the possibility of generating an HEVC encoded Processed Video Sequence (PVS) in such a way that its perceptual quality is as similar as possible to that of an AVC encoded PVS whose quality has already been assessed by human subjects. In this way, the perceptual quality of the newly generated HEVC encoded PVS may be annotated approximately with the Mean Opinion Score (MOS) of the related AVC encoded PVS. To show the effectiveness of our approach, we compared the performance of a simple and low complexity but yet effective no reference hybrid model trained on the data generated with our approach with the same model trained on data collected in the context of a pristine subjective experiment. In addition, we merged seven subjective experiments such that they can be used as one aligned dataset containing either original HEVC bitstreams or the newly generated data explained in our proposed approach. The merging process accounts for the differences in terms of quality scale, chosen assessment method and context influence factors. This yields a large annotated dataset of HEVC sequences that is made publicly available for the design and training of no reference hybrid VQMs for HEVC encoded content.
  • Angewandte Informatik
  • DIGITAL
Zeitschriftenartikel

  • L. Tiotsop
  • T. Mizdos
  • M. Uhrina
  • Marcus Barkowsky
  • P. Pocta
  • E. Masala

Modeling and estimating the subjects’ diversity of opinions in video quality assessment: a neural network based approach

In: Multimedia Tools and Applications vol. 80 pg. 3469-3487.

  • (2021)

DOI: 10.1007/s11042-020-09704-w

Abstract anzeigen

Subjective experiments are considered the most reliable way to assess the perceived visual quality. However, observers’ opinions are characterized by large diversity: in fact, even the same observer is often not able to exactly repeat his first opinion when rating again a given stimulus. This makes the Mean Opinion Score (MOS) alone, in many cases, not sufficient to get accurate information about the perceived visual quality. To this aim, it is important to have a measure characterizing to what extent the observed or predicted MOS value is reliable and stable. For instance, the Standard deviation of the Opinions of the Subjects (SOS) could be considered as a measure of reliability when evaluating the quality subjectively. However, we are not aware of the existence of models or algorithms that allow to objectively predict how much diversity would be observed in subjects’ opinions in terms of SOS. In this work we observe, on the basis of a statistical analysis made on several subjective experiments, that the disagreement between the quality as measured by means of different objective video quality metrics (VQMs) can provide information on the diversity of the observers’ ratings on a given processed video sequence (PVS). In light of this observation we: i) propose and validate a model for the SOS observed in a subjective experiment; ii) design and train Neural Networks (NNs) that predict the average diversity that would be observed among the subjects’ ratings for a PVS starting from a set of VQMs values computed on such a PVS; iii) give insights into how the same NN based approach can be used to identify potential anomalies in the data collected in subjective experiments.
  • Angewandte Informatik
  • DIGITAL
Zeitschriftenartikel

  • T. Mizdos
  • Marcus Barkowsky
  • M. Uhrina
  • P. Pocta

How to reuse existing annotated image quality datasets to enlarge available training data with new distortion types

In: Multimedia Tools and Applications vol. 80 pg. 28137–28159.

  • (2021)

DOI: 10.1007/s11042-021-10679-5

Abstract anzeigen

There is a continuing demand for objective measures that predict perceived media quality. Researchers are developing new methods for mapping technical parameters of digital media to the perceived quality. It is quite common to use machine learning algorithms for these purposes especially deep learning algorithms, which need large amounts of data for training. In this paper, we aim towards getting more training data with recent types of distortions. Instead of doing expensive subjective experiments, we evaluate the reuse of previously published, well-known image datasets with subjective annotation. In this contribution, the procedure of mapping Mean Opinion Scores (MOS) from an already published subjectively annotated dataset with older codecs to new codecs is presented. In particular, we map from Joint Photographic Experts Group (JPEG) distortions to newer High Efficiency Video Coding (HEVC) distortions. We have used values of three different objective methods as a connection between these two different distortion types. In order to investigate the significance of our approach, subjective verification tests were designed and conducted. The design goals led to two types of experiments, i.e. Pair Comparison (PC) test and Absolute Category Rating (ACR) test, in which 40 participants provided their opinion. Results of the subjective experiments indicate that it may be possible to use information gained from older datasets to describe the perceived quality of more recent compression algorithms.
  • Angewandte Informatik
  • DIGITAL
Zeitschriftenartikel

  • L. Tiotsop
  • F. Agboma
  • G. van Wallendael
  • A. Aldahdooh
  • S. Bosse
  • L. Janowski
  • Marcus Barkowsky
  • E. Masala

On the Link Between Subjective Score Prediction and Disagreement of Video Quality Metrics

In: IEEE Access vol. 9 pg. 152923-152937.

  • (2021)

DOI: 10.1109/ACCESS.2021.3127395

Abstract anzeigen

Several video quality metrics (VQMs) have been proposed in many publications to predict how humans perceive video quality. It is common to observe significant disagreements amongst the quality predictions of these VQMs for the same video sequence. Following an extensive literature search, we found no publicised work that has investigated if such disagreements convey useful information on the accuracy of VQMs. Herein, a measure for quantifying the disagreement between VQMs is proposed. A small-scale subjective study is carried out to assess the effectiveness of our proposal. In particular, the proposed disagreement measure is shown to be extremely effective in determining whether the quality of any given processed video sequence (PVS) can be accurately predicted by the VQMs. This type of information is particularly useful for identifying video sequences that are likely to degrade the end-user’s quality of experience (QoE). Our proposal is also useful in selecting the most effective PVSs to be employed in a subjective test. We show that the proposed disagreement measure can be effectively predicted from bitstream features. This establishes a link between the capability to accurately assess the quality of a PVS and the way it is encoded. In addition, an analysis is conducted to compare the performances of some well-known and widely used open-source metrics and two proprietary metrics. The two proprietary metrics are used by a large media company for enhancing its delivery pipeline. The outcome of this comparison highlights the suitability of the open-source VQM, Video Multi-method Assessment Fusion (VMAF), as a good benchmark quality measure for both the industrial and academic environments.
  • Angewandte Informatik
  • DIGITAL
Beitrag (Sammelband oder Tagungsband)

  • L. Tiotsop
  • T. Mizdos
  • M. Uhrina
  • P. Pocta
  • Marcus Barkowsky
  • E. Masala

Predicting Single Observers Votes from Objective Measures using Neural Networks

  • (2020)
  • Angewandte Informatik
  • DIGITAL
Beitrag (Sammelband oder Tagungsband)

  • Katharina Heydn
  • Marc-Philipp Dietrich
  • Marcus Barkowsky
  • Götz Winterfeldt
  • S. Mammen
  • A. Nüchter

The Golden Bullet: A Comparative Study for Target Acquisition, Pointing and Shooting

  • (2019)

DOI: 10.1109/VS-Games.2019.8864589

Abstract anzeigen

In this study, we evaluate an interaction sequence performed by six modalities consisting of desktop-based (DB) and virtual reality (VR) environments using different input devices. For the given study, we implemented a vertical prototype of a first person shooter (FPS) game scenario, focusing on the genre-defining point-and-shoot mechanic. We introduce measures to evaluate the success of the according interaction sequence (times for target acquisition, pointing, shooting, overall net time, and number of shots) and conduct experiments to record and compare the users' performances. We show that interacting using head-tracking for landscape-rotation is performing similarly to the input of a screen-centered mouse and also yielded shortest times in target acquisition and pointing. Although using head-tracking for target acquisition and pointing was most efficient, subjects rated the modality using head-tracking for target acquisition and a 3DOF Controller for pointing best. Eye-tracking (ET) yields promising results, but calibration issues need to be resolved to enhance reliability and overall user experience.
  • Angewandte Informatik
  • DIGITAL
Zeitschriftenartikel

  • T. Mizdos
  • Marcus Barkowsky
  • M. Uhrina
  • P. Pocta

Linking Bitstream Information to QoE: A Study on Still Images Using HEVC Intra Coding

In: Advances in Electrical and Electronic Engineering vol. 17 pg. 436-445.

  • (2019)

DOI: 10.15598/aeee.v17i4.3625

Abstract anzeigen

The coding tools used in image and video encoders aim at high perceptual quality for low bitrates. Analyzing the results of the encoders in terms of quantization parameter, image partitioning, prediction modes or residuals may provide important insight into the link between those tools and the human perception. As a first step, this contribution analyzes the possibility to transcode reference images of three well-known image databases, i.e. IRCCyN/IVC, LIVE and TID2013, from their original, older formats to HEVC; thus creating a homogeneous database of 327 HEVC encoded images accompanied with bitstream parameters and values obtained from objective and subjective assessments. Secondly, it analyzes some of the HEVC intra coding parameters regarding their influence on the image quality by using machine learning, namely Support Vector Machine - Regression.
  • Angewandte Informatik
  • DIGITAL
Beitrag (Sammelband oder Tagungsband)

  • L. Tiotsop
  • E. Masala
  • A. Aldahdooh
  • G. Wallendael
  • Marcus Barkowsky

Computing Quality-of-Experience Ranges for Video Quality Estimation

  • (2019)

DOI: 10.1109/QoMEX.2019.8743303

Abstract anzeigen

Typically, the measurement of the Quality of Experience for video sequences aims at a single value, in most cases the Mean Opinion Score (MOS). Predicting this value using various algorithms has been widely studied. However, deviation from the MOS is often handled as an unpredictable error. The approach in this contribution estimates intervals of video quality instead of the single valued MOS. Well-known video quality estimators are fused together to output a lower and upper border for the expected video quality, on the basis of a model derived from a well-known subjectively annotated dataset. Results on different datasets provide insight on the suitability of the well-known estimators for this particular approach.
  • Angewandte Informatik
  • DIGITAL
Zeitschriftenartikel

  • K. Brunnström
  • Marcus Barkowsky

Statistical quality of experience analysis: on planning the sample size and statistical significance testing

In: Journal of Electronic Imaging vol. 27 pg. 053013.

  • (2018)

DOI: 10.1117/1.JEI.27.5.053013

Abstract anzeigen

This paper analyzes how an experimenter can balance errors in subjective video quality tests between the statistical power of finding an effect if it is there and not claiming that an effect is there if the effect is not there, i.e., balancing Type I and Type II errors. The risk of committing Type I errors increases with the number of comparisons that are performed in statistical tests. We will show that when controlling for this and at the same time keeping the power of the experiment at a reasonably high level, it is unlikely that the number of test subjects that are normally used and recommended by the International Telecommunication Union (ITU), i.e., 15 is sufficient but the number used by the Video Quality Experts Group (VQEG), i.e., 24 is more likely to be sufficient. Examples will also be given for the influence of Type I error on the statistical significance of comparing objective metrics by correlation. We also present a comparison between parametric and nonparametric statistics. The comparison targets the question whether we would reach different conclusions on the statistical difference between the video quality ratings of different video clips in a subjective test, based on the comparison between the student T-test and the Mann‐Whitney U-test. We found that there was hardly a difference when few comparisons are compensated for, i.e., then almost the same conclusions are reached. When the number of comparisons is increased, then larger and larger differences between the two methods are revealed. In these cases, the parametric T-test gives clearly more significant cases, than the nonparametric test, which makes it more important to investigate whether the assumptions are met for performing a certain test.
  • Angewandte Informatik
  • DIGITAL
Zeitschriftenartikel

  • J. Li
  • Wang, J.
  • Marcus Barkowsky
  • P. Callet

Exploring the effects of subjective methodology on assessing visual discomfort in immersive multimedia

In: Electronic Imaging, Human Vision and Electronic Imaging

  • (2018)

DOI: 10.2352/ISSN.2470-1173.2018.14.HVEI-527

Abstract anzeigen

Visual discomfort is an important factor that influences viewing experience in immersive multimedia, for example, 3DTV and VR. With the added value of depth, the novel perceptual experience, visual discomfort is not an easy task for observers to evaluate. In this study, we investigate how the subjective methodology affects the test results in 3DTV condition. Two subjective visual discomfort experiments were conducted. One used the Pair Comparison (PC) method and the other used the Absolute-Category Rating (ACR) method. The results demonstrated that PC method had more powerful discriminability. For a difficult perceptualrelated tasks, such as visual discomfort in our study, PC was more easy to understand and conduct for the observers which led to reliable results. It also showed some very important but usually ignored conclusions on the subjective experiment, i.e., for measuring the perceived visual discomfort, the observer\textquoterights judgment behavior might be affected by the test methodology.
  • Angewandte Informatik
  • DIGITAL
Beitrag (Sammelband oder Tagungsband)

  • A. Aldahdooh
  • E. Masala
  • O. Janssens
  • G. Wallendael
  • Marcus Barkowsky

Comparing simple video quality measures for loss-impaired video sequences on a large-scale database

pg. 1-6.

  • (2016)

Abstract anzeigen

The performance of objective video quality measures is usually identified by comparing their predictions to subjective assessment results which are regarded as the ground truth. In this work we propose a complementary approach for this performance evaluation by means of a large-scale database of test sequences evaluated with several objective measurement algorithms. Such an approach is expected to detect performance anomalies that could highlight shortcomings in current objective measurement algorithms. Using realistic coding and network transmission conditions, we investigate the consistency of the prediction of different measures as well as how much their behavior can be predicted by content, coding and transmission features, discussing unexpected and peculiar behaviors, and highlighting how a large-scale database can help in identifying anomalies not easily found by means of subjective testing. We expect that this analysis will shed light on directions to pursue in order to overcome some of the limitations of existing reliability assessment methods for objective video quality measures.
  • Angewandte Informatik
  • DIGITAL
Beitrag (Sammelband oder Tagungsband)

  • A. Aldahdooh
  • Marcus Barkowsky
  • P. Callet

Spatio-temporal error concealment technique for high order multiple description coding schemes including subjective assessment

pg. 1-6.

  • (2016)

Abstract anzeigen

Error resilience (ER) is an important tool in video coding to maximize the quality of Experience (QoE). The prediction process in video coding became complex which yields an unsatisfying video quality when NALunit packets are lost in error-prone channels. There are different ER techniques and multiple description coding (MDC) is one of the promising technique for this problem. MDC is categorized into different types and, in this paper, we focus on temporal MDC techniques. In this paper, a new temporal MDC scheme is proposed. In the encoding process, the encoded descriptions contain primary frames and secondary frames (redundant representations). The secondary frames represent the MVs that are predicted from previous primary frames such that the residual signal is set to zero and is not part of the rate distortion optimization. In the decoding process of the lost frames, a weighted average error concealment (EC) strategy is proposed to conceal these frames. The proposed scheme is subjectively evaluated along with other schemes and the results show that the proposed scheme is significantly different from most of other temporal MDC schemes.
  • Angewandte Informatik
  • DIGITAL
Beitrag (Sammelband oder Tagungsband)

  • K. Berger
  • Y. Koudota
  • Marcus Barkowsky
  • P. Le Callet

Subjective Quality Assessment Comparing UHD and HD Resolution in HEVC Transmission Chain

  • (2015)

Abstract anzeigen

Ultra High Definition Television (UHDTV) is an emerging broadcasting system, aiming to replace the current High Definition Television (HDTV) in the near future. One aspect of UHDTV is to allow for higher resolutions, notably UHD1, which requires a four times increased datarate for uncompressed transmission compared to Full-HD resolution. As bandwidth for transmission channels in television broadcast is often a fixed value, this study provides information about the perceived quality for transmitting UHD1 content compared to Full-HD content at the same bitrate encoded with HEVC. Content influence is tested with 15 video contents and 4 bitrates are individually chosen per content to span the range of the perceptual scale. The methodology of Absolute Category Rating with Hidden Reference (ACR-HR) is used to collect votes from 24 viewers. The statistical analysis of the collected data shows that, in most cases, there is no significant quality difference between videos transmitted in Full-HD and UHD1 resolution but that the results strongly depend on the content type and on the capture quality. It is also shown that the required bitrate for achieving a chosen broadcast quality level varies with content by a factor of about 14 in HEVC coding.
  • Angewandte Informatik
  • DIGITAL
Zeitschriftenartikel

  • J. Li
  • A. Wang
  • Wang, J.
  • Marcus Barkowsky
  • P. Le Callet

Visual Discomfort Induced by Three-Dimensional Display Technology (in Chinese)

In: Laser and Optoelectronics Progress vol. 52

  • (2015)
  • Angewandte Informatik
  • DIGITAL
Zeitschriftenartikel

  • Marcus Barkowsky
  • E. Masala
  • G. van Wallendael
  • K. Brunnström
  • N. Staelens
  • P. Le Callet

Objective Video Quality Assessment ‐- Towards Large Scale Video Database Enhanced Model Development

In: IEICE Transactions on Communications vol. E-98b pg. 2-11.

  • (2015)

Abstract anzeigen

The current development of video quality assessment algorithms suffers from the lack of available video sequences for training, verification and validation to determine and enhance the algorithm's application scope. The Joint Effort Group of the Video Quality Experts Group (VQEG-JEG) is currently driving efforts towards the creation of large scale, reproducible, and easy to use databases. These databases will contain bitstreams of recent video encoders (H.264, H.265), packet loss impairment patterns and impaired bitstreams, pre-parsed bitstream information into files in XML syntax, and well-known objective video quality measurement outputs. The database is continuously updated and enlarged using reproducible processing chains. Currently, more than 70,000 sequences are available for statistical analysis of video quality measurement algorithms. New research questions are posed as the database is designed to verify and validate models on a very large scale, testing and validating various scopes of applications, while subjective assessment has to be limited to a comparably small subset of the database. Special focus is given on the principles guiding the database development, and some results are given to illustrate the practical usefulness of such a database with respect to the detailed new research questions.
  • Angewandte Informatik
  • DIGITAL
Beitrag (Sammelband oder Tagungsband)

  • M. Shahid
  • J. Panasiuk
  • G. van Wallendael
  • Marcus Barkowsky
  • B. Lovstrom

Predicting full-reference video quality measures using HEVC bitstream-based no-reference features

pg. 1-2.

  • (2015)

Abstract anzeigen

This paper presents bitstream-based features for perceptual quality estimation of HEVC coded videos. Various factors including the impact of different sizes of block-partitions, use of reference-frames, the relative amount of various prediction modes, statistics of motion vectors and quantization parameters are taken into consideration for producing 52 features relevant for perceptual quality prediction. The used test stimuli constitutes 560 bitstreams that have been carefully extracted for this analysis from the 59, 520 bistreams of the large-scale database generated by the Joint Effort Group (JEG) of the Video Quality Experts Group (VQEG). The obtained results show the significance of the considered features through reasonably accurate and monotonic prediction of a number of objective quality metrics.
  • Angewandte Informatik
  • DIGITAL
Beitrag (Sammelband oder Tagungsband)

  • Y. Rai
  • Marcus Barkowsky
  • P. Le Callet

Does H.265 based peri and para-foveal quality flicker disrupt natural viewing patterns?

pg. 133-136.

  • (2015)

Abstract anzeigen

Region of interest based coders and also those coders that extensively use the Intra coding mode tend to produce flickering artefacts due to the inherent quality fluctuations they produce in the non-salient or homogeneously textured intra coded regions of a scene respectively. These non-salient areas are in turn incident on the para, peri and extra-peri foveal retinal regions that are especially sensitive to temporal artefacts. To study the perceptual effects of such a quality based flicker in the retinal periphery, in this experiment gaze data was collected from 48 observers in a free viewing scenario using a regulated flicker stimulus. The video stimulus in the mentioned peripheral regions were flickered with a predetermined frequency and amplitude by adaptively combining the streams produced using a H.265 video coder, and presenting them in a Gaze Contingent Display(GCD) setup. Utilizing statistical gaze analysis techniques, we observe that, temporal quality flicker in the visual periphery plays a major role in disturbing the natural viewing patterns of an observer. Further, this effect was found to be maximum in the 7.5Hz temporal band thus showing that, encoders that affect temporal quality smoothness must aim to avoid such distraction effects.
  • Angewandte Informatik
  • DIGITAL
Beitrag (Sammelband oder Tagungsband)

  • P. Lebreton
  • Marcus Barkowsky
  • A. Raake
  • P. Le Callet

Chapter 20: 3D Video

In: Quality of Experience: Advanced Concepts, Applications and Methods. null (T-Labs Series in Telecommunication Services) pg. 299-313.

  • (2014)
  • Angewandte Informatik
  • DIGITAL
Beitrag (Sammelband oder Tagungsband)

  • P. Lebreton
  • A. Raake
  • Marcus Barkowsky
  • P. Le Callet

Measuring perceived depth in natural images and study of its relation with monocular and binocular depth cues

pg. 1.

San Francisco, CA, USA

  • (2014)

Abstract anzeigen

The perception of depth in images and video sequences is based on different depth cues. Studies have considered depth perception threshold as a function of viewing distance (Cutting & Vishton,1995), the combination of different monocular depth cues and their quantitative relation with binocular depth cues and their different possible type of interactions (Landy,1995). But these studies only consider artificial stimuli and none of them attempts to provide a quantitative contribution of monocular and binocular depth cues compared to each other in the specific context of natural images. This study targets this particular application case. The evaluation of the strength of different depth cues compared to each other using a carefully designed image database to cover as much as possible different combinations of monocular (linear perspective, texture gradient, relative size and defocus blur) and binocular depth cues. The 200 images were evaluated in two distinct subjective experiments to evaluate separately perceived depth and different monocular depth cues. The methodology and the description of the definition of the different scales will be detailed. The image database is also released for the scientific community.
  • Angewandte Informatik
  • DIGITAL
Zeitschriftenartikel

  • J. Li
  • Marcus Barkowsky
  • P. Le Callet

Validation of reliable 3DTV subjective assessment methodology ‐ Establishing a Ground Truth Database

In: VQEG (Video Quality Expert Group) eLetter vol. 1

  • (2014)

Abstract anzeigen

Quality of Experience (QoE) in 3DTV is a multi-dimensional concept which includes image quality, depth quality, and visual comfort. How to measure this multi-dimensional concept is a challenging issue nowadays. In this letter, we introduce a Ground Truth database which is targeted for the standardization of subjective methodologies for QoE in 3DTV.
  • Angewandte Informatik
  • DIGITAL
Zeitschriftenartikel

  • J. Li
  • Marcus Barkowsky
  • P. Callet

Visual discomfort of stereoscopic 3D videos: Influence of 3D motion

In: Displays vol. 35 pg. 49-57.

  • (2014)

DOI: 10.1016/j.displa.2014.01.002

Abstract anzeigen

Visual discomfort is one of the most frequent complaints of the viewers while watching 3D images and videos. Large disparity and large amount of motion are two main causes of visual discomfort. To quantify this influence, three objectives are set in this paper. The first one is the comparative analysis on the influence of different types of motion, i.e., static stereoscopic image, planar motion and in-depth motion, on visual discomfort. The second one is the investigation on the influence factors for each motion type, for example, the disparity offset, the disparity amplitude and velocity. The third one is to propose an objective model for visual discomfort. Thirty-six synthetic stereoscopic video stimuli with different types of motion are used in this study. In the subjective test, an efficient paired comparison method called Adaptive Square Design (ASD) was used to reduce the number of comparisons for each observer and keep the results reliable. The experimental results showed that motion does not always induce more visual discomfort than static conditions. The in-depth motion generally induces more visual discomfort than the planar motion. The relative disparity between the foreground and the background, and the motion velocity are identified as main factors for visual discomfort. According to the subjective results, an objective model for comparing visual discomfort induced by different types of motion is proposed which shows high correlation with the subjective perception.
  • Angewandte Informatik
  • DIGITAL
Beitrag (Sammelband oder Tagungsband)

  • J. Li
  • Marcus Barkowsky
  • P. Le Callet

Assessing the Quality of Experience of 3DTV and Beyond: Tackling the Multidimensional Sensation

pg. 201-222.

New York

  • (2014)
  • Angewandte Informatik
  • DIGITAL
Zeitschriftenartikel

  • Marcus Barkowsky
  • I. Sedano
  • K. Brunnström
  • M. Leszczuk
  • N. Staelens

Hybrid video quality prediction: reviewing video quality measurement for widening application scope

In: Multimedia Tools and Applications vol. 74 pg. 323-343.

Springer US

  • (2014)

DOI: 10.1007/s11042-014-1978-2

Abstract anzeigen

A tremendous number of objective video quality measurement algorithms have been developed during the last two decades. Most of them either measure a very limited aspect of the perceived video quality or they measure broad ranges of quality with limited prediction accuracy. This paper lists several perceptual artifacts that may be computationally measured in an isolated algorithm and some of the modeling approaches that have been proposed to predict the resulting quality from those algorithms. These algorithms usually have a very limited application scope but have been verified carefully. The paper continues with a review of some standardized and well-known video quality measurement algorithms that are meant for a wide range of applications, thus have a larger scope. Their individual artifacts prediction accuracy is usually lower but some of them were validated to perform sufficiently well for standardization. Several difficulties and shortcomings in developing a general purpose model with high prediction performance are identified such as a common objective quality scale or the behavior of individual indicators when confronted with stimuli that are out of their prediction scope. The paper concludes with a systematic framework approach to tackle the development of a hybrid video quality measurement in a joint research collaboration.
  • Angewandte Informatik
  • DIGITAL
Zeitschriftenartikel

  • M. Urvoy
  • Marcus Barkowsky
  • P. Le Callet

How visual fatigue and discomfort impact 3D-TV quality of experience: a comprehensive review of technological, psychophysical, and psychological factors

In: Annales des Télécommunications vol. 68 pg. 641-655.

  • (2013)

DOI: 10.1007/s12243-013-0394-3

Abstract anzeigen

The quality of experience (QoE) of 3D contents is usually considered to be the combination of the perceived visual quality, the perceived depth quality, and lastly the visual fatigue and comfort. When either fatigue or discomfort are induced, studies tend to show that observers prefer to experience a 2D version of the contents. For this reason, providing a comfortable experience is a prerequisite for observers to actually consider the depth effect as a visualization improvement. In this paper, we propose a comprehensive review on visual fatigue and discomfort induced by the visualization of 3D stereoscopic contents, in the light of physiological and psychological processes enabling depth perception. First, we review the multitude of manifestations of visual fatigue and discomfort (near triad disorders, symptoms for discomfort), as well as means for detection and evaluation. We then discuss how, in 3D displays, ocular and cognitive conflicts with real world experience may cause fatigue and discomfort; these includes the accommodation-vergence conflict, the inadequacy between presented stimuli and observers depth of focus, and the cognitive integration of conflicting depth cues. We also discuss some limits for stereopsis that constrain our ability to perceive depth, and in particular the perception of planar and in-depth motion, the limited fusion range, and various stereopsis disorders. Finally, this paper discusses how the different aspects of fatigue and discomfort apply to 3D technologies and contents. We notably highlight the need for respecting a comfort zone and avoiding camera and rendering artifacts. We also discuss the influence of visual attention, exposure duration, and training. Conclusions provide guidance for best practices and future research.
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Beitrag (Sammelband oder Tagungsband)

  • Marcus Barkowsky
  • N. Staelens
  • L. Janowski

Open collaboration on hybrid video quality models ‐ VQEG joint effort group hybrid

pg. 476-481.

  • (2013)

Abstract anzeigen

Several factors limit the advances on automatizing video quality measurement. Modelling the human visual system requires multi- and interdisciplinary efforts. A joint effort may bridge the large gap between the knowledge required in conducting a psychophysical experiment on isolated visual stimuli to engineering a universal model for video quality estimation under real-time constraints. The verification and validation requires input reaching from professional content production to innovative machine learning algorithms. Our paper aims at highlighting the complex interactions and the multitude of open questions as well as industrial requirements that led to the creation of the Joint Effort Group in the Video Quality Experts Group. The paper will zoom in on the first activity, the creation of a hybrid video quality model.
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Zeitschriftenartikel

  • W. Chen
  • J. Fournier
  • Marcus Barkowsky
  • P. Le Callet

Methodologies for Assessing 3D QoE: Standards and Explorative Studies

In: ZTE Communications vol. 11 pg. 2-10.

  • (2013)

Abstract anzeigen

Mastering quality of experience (QoE) is key to the widespread adoption of stereoscopic 3DTV (S-3DTV). However, assessing QoE of S-3DTV is not straightforward. Methods for determining observer experience need to be clearly defined and sufficiently robust. In this paper, we present state-of-the-art subjective QoE assessment for S-3DTV. We present conventional stan⁃ dardized ITU recommendations for evaluating picture quality and discuss new ITU activities in the area of S-3DTV assess⁃ ment. We also present and discuss explorative studies from the literature. We then introduce ways of using conventional quality assessment for S-3DTV QoE assessment. In discussing our pro⁃ posal, we mainly focus on QoE indicators and common features of subjective assessment. Multidimensional QoE indicators need to be used in S-3DTV to highlight advantages and reveal problems. In the second part of our proposal, we discuss the re⁃ quirements for adapting ITU-R BT.500, a conventional subjec⁃ tive QoE assessment method, ITU-R BT.500, for assessing QoE of S-3DTV are presented.
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Beitrag (Sammelband oder Tagungsband)

  • Marcus Barkowsky
  • J. Li
  • T. Han
  • S. Youn
  • J. Ok
  • C. Lee
  • I. Vijai Ananth
  • K. Wang
  • K. Brunnström
  • P. Le Callet

Towards standardized 3DTV QoE assessment: Cross-lab study on display technology and viewing environment parameters

  • (2013)

Abstract anzeigen

Subjective assessment of Quality of Experience in stereoscopic 3D requires new guidelines for the environmental setup as existing standards such as ITU-R BT.500 may no longer be appropriate. A first step is to perform cross-lab experiments in different viewing conditions on the same video sequences. Three international labs performed Absolute Category Rating studies on a freely available video database containing degradations that are mainly related to video quality degradations. Different conditions have been used in the labs: Passive polarized displays, active shutter displays, differences in viewing distance, the number of parallel viewers, and the voting device. Implicit variations were introduced due to the three different languages in Sweden, South Korea, and France. Although the obtained Mean Opinion Scores are comparable, slight differences occur in function of the video degradations and the viewing distance. An analysis on the statistical differences obtained between the MOS of the video sequences revealed that obtaining an equivalent number of differences may require more observers in some viewing conditions. It was also seen that the alignment of the meaning of the attributes used in Absolute Category Rating in different languages may be beneficial. Statistical analysis was performed showing influence of the viewing distance on votes and MOS results.
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Beitrag (Sammelband oder Tagungsband)

  • J. Li
  • Marcus Barkowsky
  • P. Le Callet

Subjective Assessment Methodology For Preference Of Experience In 3dtv

pg. 1.

Seoul, South Korea

  • (2013)

Abstract anzeigen

The measurement of the Quality of Experience (QoE) in 3DTV re- cently became an important research topic as it relates to the devel- opment of the 3D industry. Pair comparison is a reliable method as it is easier for the observers to provide their preference on a pair rather than give an absolute scale value to a stimulus. The QoE measured by pair comparison is thus called \textquoteright. In this paper, we introduce some efficient designs for pair compari- son which can reduce the number of comparisons. The constraints of the presentation order of the stimuli in pair comparison test are listed. Finally, some analysis methods for pair comparison data are provided accompanied with some examples from the studies of the measurement of PoE.
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Beitrag (Sammelband oder Tagungsband)

  • M. Urvoy
  • Marcus Barkowsky
  • J. Li
  • P. Le Callet

Visual Comfort and Fatigue in Stereoscopy

pg. 309-329.

London, UK

  • (2013)
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Beitrag (Sammelband oder Tagungsband)

  • M. Leszczuk
  • L. Janowski
  • Marcus Barkowsky

Freely Available Large-scale Video Quality Assessment Database in Full-HD Resolution with H.264 Coding

vol. - pg. 1.

Atlanta, GA, USA

  • (2013)

Abstract anzeigen

Video databases often focus on a particular use case with a limited set of sequences. In this paper, a different type of database creation is proposed: an exhaustive number of test conditions will be continuously created and made freely available for objective and subjective evaluation. At the moment, the database comprises more than ten thousand JM/x264-encoded video sequences. An extensive study of the possible encoding parameter space led to a first subset selection of 1296 configura- tions. At the moment, only ten source sequences have been used, but extension to more than one hundred sequences is planned. Some Full-Reference (FR) and No-Reference (NR) metrics were selected and calculated. The resulting data will be freely available to the research community and possible exploitation areas are suggested.
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Beitrag (Sammelband oder Tagungsband)

  • P. Lebreton
  • A. Raake
  • Marcus Barkowsky
  • P. Le Callet

Perceptual preference of S3D over 2D for HDTV in dependence of video quality and depth

pg. 1-4.

  • (2013)

Abstract anzeigen

3D video quality of experience (QoE) is a multidimensional problem and many factors contribute to the global experience by the user. Due to this multidimensionality, this paper evaluates the integral 3D video QoE and relates it with image quality and depth. Subjective tests have been conducted using paired comparison to evaluate 3D QoE and the preference of 3D over 2D with different combinations of coding conditions. Depth scores were available from previous work and were used to check their relation with 3DQoE; the difference between 2D and 3D QoE is found to be a function of the picture quality, and the desired preference of 3D presentation over 2D can be reached when pictorial quality is high enough (VQM score lower than 0.24). A factor ranging from 0.08 to 0.76 with a mean of 0.71 between pictorial quality and preference of 3D was also found.
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Beitrag (Sammelband oder Tagungsband)

  • K. Wang
  • K. Brunnström
  • Marcus Barkowsky
  • M. Urvoy
  • M. Sjöström
  • P. Le Callet
  • S. Tourancheau
  • B. Andrén

Stereoscopic 3D video coding quality evaluation with 2D objective metrics

  • (2013)

Abstract anzeigen

The 3D video quality is of highest importance for the adoption of a new technology from a user’s point of view. In this paper we evaluated the impact of coding artefacts on stereoscopic 3D video quality by making use of several existing full reference 2D objective metrics. We analyzed the performance of objective metrics by comparing to the results of subjective experiment. The results show that pixel based Visual Information Fidelity metrics fits subjective data the best. The 2D stereoscopic video quality seems to have dominant impact on the coding artefacts impaired stereoscopic videos.
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Zeitschriftenartikel

  • M. Pinson
  • Marcus Barkowsky
  • P. Le Callet

Selecting scenes for 2D and 3D subjective video quality tests

In: EURASIP Journal on Image and Video Processing pg. Article number: 50.

  • (2013)

Abstract anzeigen

This paper presents recommended techniques for choosing video sequences for subjective experiments. Subjective video quality assessment is a well-understood field, yet scene selection is often driven by convenience or content availability. Three-dimensional testing is a newer field that requires new considerations for scene selection. The impact of experiment design on best practices for scene selection will also be considered. A semi-automatic selection process for content sets for subjective experiments will be proposed.
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Beitrag (Sammelband oder Tagungsband)

  • S. Tourancheau
  • K. Wang
  • J. Bulat
  • R. Cousseau
  • L. Janowski
  • K. Brunnström
  • Marcus Barkowsky

Reproducibility of crosstalk measurements on active glasses 3D LCD displays based on temporal characterization

  • (2012)

Abstract anzeigen

Crosstalk is one of the main display-related perceptual factors degrading image quality and causing visual dis-comfort on 3D-displays. It causes visual artifacts such as ghosting eects, blurring, and lack of color delitywhich are considerably annoying and can lead to diculties to fuse stereoscopic images. On stereoscopic LCDwith shutter-glasses, crosstalk is mainly due to dynamic temporal aspects: imprecise target luminance (highlydependent on the combination of left-view and right-view pixel color values in disparity regions) and synchro-nization issues between shutter-glasses and LCD. These dierent factors inuence largely the reproducibilityof crosstalk measurements across laboratories and need to be evaluated in several dierent locations involvingsimilar and diering conditions. In this paper we propose a fast and reproducible measurement procedure forcrosstalk based on high-frequency temporal measurements of both display and shutter responses. It permitsto fully characterize crosstalk for any right/left color combination and at any spatial position on the screen.Such a reliable objective crosstalk measurement method at several spatial positions is considered a mandatoryprerequisite for evaluating the perceptual inuence of crosstalk in further subjective studies.
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Beitrag (Sammelband oder Tagungsband)

  • Y. Pitrey
  • R. Pépion
  • P. Le Callet
  • Marcus Barkowsky

Using overlapping subjective datasets to assess the performance of objective quality metrics on Scalable Video Coding and error concealment

pg. 103.

Melbourne, Australia

  • (2012)

Abstract anzeigen

In this paper, four subjective video datasets are presented. The considered application is Scalable Video Coding used as an error-concealment mechanism. The presented datasets explore the relations between encoding parameters and perceived quality, under different network-impairment patterns and involve error-concealment on the decoder\textquoterights side, to simulate a complete distribution channel. The datasets share a part of common configurations which enables, in the first part of the paper, to compare the outcomes from several Single Stimulus experiments and draw interesting correspondances between different types of distortion. In the second part of the paper, we analyse the performance of three common objective quality metrics on each step of the distribution channel, to identify the possible directions to be followed in order to improve their accuracy in predicting the perceived quality.
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Beitrag (Sammelband oder Tagungsband)

  • P. Lebreton
  • A. Raake
  • Marcus Barkowsky
  • P. Le Callet

Perceptual depth indicator for S-3D content based on binocular and monocular cues

pg. 734-738.

  • (2012)

Abstract anzeigen

This article describes a general depth indicator for stereoscopic 3D video sequences. This indicator targets the characterization of the depth in 3D video sequences based on both monocular and binocular depth cues. Evaluating monocular depth cues is no easy task. Due to this high complexity, only a subset of the monocular depth cues are currently considered since it is believed that they play a major impact in depth perception. The proposed algorithm will consider the following different depth cues: binocular depth, linear perspective, blur from defocus, motion parallax and texture gradient. It will be detailed how all these all metrics have been designed. The second main contribution is the definition of a specific application scope of each metrics. This is motivated by the need to take into account the reliability of each individual metrics during the pooling. Therefore, it will be considered in the paper to identify the cases where each individual metric may fail and integrate these aspects in the general combination of the depth cues.
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Beitrag (Sammelband oder Tagungsband)

  • J. Li
  • Marcus Barkowsky
  • P. Le Callet

Analysis and Improvement of a Paired Comparison Method in the Application of 3DTV Subjective Experiment

  • (2012)

Abstract anzeigen

Paired comparison is a frequently used method in psychophysical studies. However, with the increase of the number of the stimuli, the number of comparisons increases exponentially. Square design is one of the balanced sub-set paired comparison methods which could reduce the number of comparisons while producing comparably precise results under some assumptions. However, when there are observation errors from observers' attentiveness, the square design would produce large estimation errors. Thus, an improved square design which is robust to observation errors is proposed. Using a Monte Carlo simulation, the proposed method is evaluated and shows improvement in efficiency. The original design is applied in a visual discomfort subjective test of 3DTV. In addition, both of the two designs are studied by utilizing our previous full comparison data. The test results showed that the proposed improved square design is more robust to observation errors. Another important finding is that the influence of the occurrence of some other stimuli on voting is significant. Whether the proposed method could reduce the prediction errors induced by it is still under study.
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Zeitschriftenartikel

  • M. Pinson
  • L. Janowski
  • R. Pepion
  • Q. Huynh-Thu
  • C. Schmidmer
  • P. Corriveau
  • A. Younkin
  • P. Le Callet
  • Marcus Barkowsky
  • W. Ingram

The Influence of Subjects and Environment on Audiovisual Subjective Tests: An International Study

In: IEEE Journal of Selected Topics in Signal Processing vol. 6 pg. 640-651.

  • (2012)

DOI: 10.1109/JSTSP.2012.2215306

Abstract anzeigen

Traditionally, audio quality and video quality are evaluated separately in subjective tests. Best practices within the quality assessment community were developed before many modern mobile audiovisual devices and services came into use, such as internet video, smart phones, tablets and connected televisions. These devices and services raise unique questions that require jointly evaluating both the audio and the video within a subjective test. However, audiovisual subjective testing is a relatively under-explored field. In this paper, we address the question of determining the most suitable way to conduct audiovisual subjective testing on a wide range of audiovisual quality. Six laboratories from four countries conducted a systematic study of audiovisual subjective testing. The stimuli and scale were held constant across experiments and labs; only the environment of the subjective test was varied. Some subjective tests were conducted in controlled environments and some in public environments (a cafeteria, patio or hallway). The audiovisual stimuli spanned a wide range of quality. Results show that these audiovisual subjective tests were highly repeatable from one laboratory and environment to the next. The number of subjects was the most important factor. Based on this experiment, 24 or more subjects are recommended for Absolute Category Rating (ACR) tests. In public environments, 35 subjects were required to obtain the same Student\textquoterights t-test sensitivity. The second most important variable was individual differences between subjects. Other environmental factors had minimal impact, such as language, country, lighting, background noise, wall color, and monitor calibration. Analyses indicate that Mean Opinion Scores (MOS) are relative rather than absolute. Our analyses show that the results of experiments done in pristine, laboratory environments are highly representative of those devices in actual use, in a typical user environment.
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Beitrag (Sammelband oder Tagungsband)

  • K. Brunnström
  • I. Sedano
  • K. Wang
  • Marcus Barkowsky
  • M. Kihl
  • P. Le Callet
  • Patrick
  • M. Sjöström
  • A. Aurelius

2D No-Reference Video Quality Model Development and 3D Video Transmission Quality

  • (2012)

Abstract anzeigen

This presentation will target two different topics in video quality assessment. First, we discuss 2D no-reference video quality model development. Further, we discuss how to find suitable quality for 3D video transmission. No-reference metrics are the only practical option for monitoring of 2D video quality in live networks. In order to decrease the development time, it might be possible to use full-reference metrics for this purpose. In this work, we have evaluated six full-reference objective metrics in three different databases. We show statistically that VQM performs the best. Further, we use these results to develop a lightweight no-reference model. We have also investigated users' experience of stereoscopic 3D video quality by performing the rating of two subjective assessment datasets, targeting in one dataset efficient transmission in the transmission error free case and error concealment in the other. Among other results, it was shown that, based on the same level of quality of experience, spatial down-sampling may lead to better bitrate efficiency while temporal down-sampling will be worse. When network impairments occur, traditional error 2D concealment methods need to be reinvestigated as they were outperformed switching to 2D presentation.
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Beitrag (Sammelband oder Tagungsband)

  • Y. Pitrey
  • P. Hummelbrunner
  • B. Kitzinger
  • S. Buchinger
  • Marcus Barkowsky
  • P. Le Callet
  • R. Pepion

Influence of Shooting Conditions, Re-Encoding and Viewing Conditions on the Perceived Quality of User-Generated Videos

  • (2012)
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Zeitschriftenartikel

  • K. Wang
  • Marcus Barkowsky
  • K. Brunnström
  • M. Sjöström
  • R. Cousseau
  • P. Le Callet

Perceived 3D TV Transmission Quality Assessment: Multi-Laboratory Results Using Absolute Category Rating on Quality of Experience Scale

In: IEEE Transactions on Broadcasting vol. 58 pg. 544-557.

  • (2012)

Abstract anzeigen

Inspired by the rapidly increasing popularity of 3D movies, there is an industrial push for 3DTV services to the home. One important factor for the success and acceptance by the viewers is a positive quality of experience (QoE) of the new service when delivered. The questions of how to efficiently deliver 3DTV service to the home, and how to evaluate the visual quality perceived by end users are a recent research focus. We have investigated users\textquoteright experience of stereoscopic 3D video quality by preparing two subjective assessment datasets. The first dataset aimed at the evaluation of efficient transmission in the transmission error free case, while the second focused on error concealment. A total of three subjective assessments, two for first dataset and one for the second, were performed using the Absolute Category Rating with Hidden unimpaired Reference video (ACR-HR) method. The experimental setup allows to show that the ACR-HR subjective method provides repeatable results across labs and across conditions for video quality. It was also verified that MVC is more efficient than H.264 simulcast coding. Furthermore it was discovered that based on the same level of quality of experience spatial down-sampling may lead to better bitrate efficiency while temporal down-sampling is not acceptable. When network impairments occur, traditional error 2D concealment methods need to be reinvestigated as they were outperformed by displaying the same view for both eyes (switching to 2D presentation).
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Zeitschriftenartikel

  • P. Lebreton
  • A. Raake
  • Marcus Barkowsky
  • P. Le Callet

Evaluating Depth Perception of 3D Stereoscopic Videos

In: IEEE Journal of Selected Topics in Signal Processing vol. 6 pg. 710-720.

  • (2012)

Abstract anzeigen

3D video quality of experience (QoE) is a multidimensional problem; many factors contribute to the global rating like image quality, depth perception and visual discomfort. Due to this multidimensionality, it is proposed in this paper, that as a complement to assessing the quality degradation due to coding or transmission, the appropriateness of the non-distorted signal should be addressed. One important factor here is the depth information provided by the source sequences. From an application-perspective, the depth-characteristics of source content are of relevance for pre-validating whether the content is suitable for 3D video services. In addition, assessing the interplay between binocular and monocular depth features and depth perception are relevant topics for 3D video perception research. To achieve the evaluation of the suitability of 3D content, this paper describes both a subjective experiment and a new objective indicator to evaluate depth as one of the added values of 3D video.
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Beitrag (Sammelband oder Tagungsband)

  • P. Lebreton
  • A. Raake
  • Marcus Barkowsky
  • P. Le Callet

A Subjective Evaluation of 3D IPTV Broadcasting Implementations Considering Coding and Transmission Degradation

pg. 506-511.

  • (2011)

Abstract anzeigen

This paper describes the results of a subjective test to assess current technology used for 3DTV broadcasting. As a first aspect, the performance of the currently deployed coding schemes was compared to state of the art algorithms. Our results show that down sampling and packing 3D stereoscopic videos according to the so called Side-By-Side format gives the highest perceived quality for a given bit rate. The second aspect of the study was to investigate how common 2D error concealment algorithms perform in case of 3D, and how their 3D-related performance compares with the 2D case. The results provide information on whether binocular suppression or binocular rivalries play the most important role for 3D video quality under transmission error. The results indicate that binocular rivalries and related visual discomfort are the dominant factors. Another aspect of the paper is a comparison of the test results with results from different labs to evaluate the repeatability of a subjective experiment in the 3D case, and to compare the employed test methodologies. Here, the study shows the variation between observers when they are rating visual discomfort and illustrates the difficulty to evaluate this new dimension.
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Beitrag (Sammelband oder Tagungsband)

  • J. Li
  • Marcus Barkowsky
  • Wang, J.
  • P. Le Callet

Study on Visual Discomfort Induced by Stimulus Movement at Fixed Depth on Stereoscopic Displays using Shutter Glasses

  • (2011)

Abstract anzeigen

Stereoscopic motion images are able to provide observers with realistic and immersive viewing experience. However, observers often experience visual discomfort during the viewing process. In this paper, we investigated the relationship between visual discomfort and the planar motion at different depth levels. The Paired Comparison method was used in the subjective experiments to allow for a precise measurement. The experimental results indicated that the relative angular disparity between foreground object and background played a more important role in determining the visual discomfort than the vergence-accommodation conflict. Furthermore, the results showed that with the increase of planar motion velocity, viewers might experience more visual discomfort. To quantify the effects of relative angular disparity and velocity on visual discomfort, two visual discomfort models were constructed. The preferred model was chosen based on the performance as well as the algorithmic complexity. This model can be used as an index for other related researches.
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Zeitschriftenartikel

  • Marcus Barkowsky
  • S. Tourancheau
  • K. Brunnström
  • K. Wang
  • B. Andrén

55.3: Crosstalk Measurements of Shutter Glasses 3D Displays

In: SID Symposium Digest of Technical Papers vol. 42 pg. 812-815.

Sid

  • (2011)

Abstract anzeigen

Crosstalk is probably one of the main perceptual factors contributing to perceived image quality and visual comfort. The Video Quality Experts Group (VQEG) within their 3D video quality project is specifying a practical measurement procedure that will produce consistent results across laboratories. This paper is part of that effort. Two different method of measuring cross talk on shutter glasses stereo displays have been studied. One is based on time average luminance measurements and the other on temporal measurements. The results show that crosstalk is roughly 0.5% but that there are differences in the crosstalk between the two eyes in the shutter glasses.
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Beitrag (Sammelband oder Tagungsband)

  • K. Wang
  • Marcus Barkowsky
  • R. Cousseau
  • K. Brunnström
  • R. Olsson
  • P. Le Callet
  • M. Sjöström

Subjective evaluation of HDTV stereoscopic videos in IPTV scenarios using absolute category rating

pg. 78631T.

  • (2011)

Abstract anzeigen

Broadcasting of high definition (HD) stereobased 3D (S3D) TV are planned, or has already begun, in Europe, the US, and Japan. Specific data processing operations such as compression and temporal and spatial resampling are commonly used tools for saving network bandwidth when IPTV is the distribution form, as this results in more efficient recording and transmission of 3DTV signals, however at the same time it inevitably brings quality degradations to the processed video. This paper investigated observers quality judgments of state of the art video coding schemes (simulcast H.264/AVC or H.264/MVC), with or without added temporal and spatial resolution reduction of S3D videos, by subjective experiments using the Absolute Category Rating method (ACR) method. The results showed that a certain spatial resolution reduction working together with high quality video compressing was the most bandwidth efficient way of processing video data when the required video quality is to be judged as "good" quality. As the subjective experiment was performed in two different laboratories in two different countries in parallel, a detailed analysis of the interlab differences was performed.
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Beitrag (Sammelband oder Tagungsband)

  • J. Li
  • Marcus Barkowsky
  • P. Le Callet

Visual Discomfort Induced by Relative Disparity and Planar Motion of Stereoscopic Images

pg. 1-2.

Nantes, France

  • (2011)

Abstract anzeigen

Viewers often complain of visual discomfort or visual fatigue after viewing the stereoscopic images. In this paper, we investigated the effects of planar motion at different depth levels on visual discomfort. In the subjective experiments, the Paired Comparison method was used to allow for a precise measurement. The Bradley-Terry model was used to analyze the subjective experimental data. The experimental results indicated that the relative angular disparity between foreground object and background played a more important role in determining the visual discomfort than the vergence-accommodation conflict. Furthermore, viewers might experience more visual discomfort with the increase of planar motion velocity. In a practical application of our study, it may be concluded that for stereoscopic motion images, the depth range for fast motion sequences should be significantly reduced and for slow motion sequences, the depth range may be increased.
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Beitrag (Sammelband oder Tagungsband)

  • Wang, J.
  • Marcus Barkowsky
  • V. Ricordel
  • P. Le Callet

Clarifying how defocus blur and disparity affect the perceived depth

pg. 1.

Nantes, France

  • (2011)

Abstract anzeigen

Human visual system takes advantage of different cues simultaneously to provide us the perception of depth. When 3D images are shown on a planar stereoscopic display, binocular disparity becomes a pre-eminent depth cue. But it induces simultaneously the conflict between accommodation and vergence, which is often considered as a main reason for visual discomfort. If we limit this visual discomfort by decreasing the disparity, the apparent depth also decreases. We propose to decrease the (binocular) disparity of 3D presentations, and to reinforce (monocular) cues to compensate the loss of perceived depth and keep an unaltered apparent depth. The influence of a monocular depth cue, blur, on the apparent depth of stereoscopic scenes was studied in our recent work. We conducted a subjective experiment using a two-alternative forced choice task. Observers were required to identify the larger perceived depth in a pair of 3D images with/without blur. By fitting the result to a psychometric function, we obtained points of subjective equality in terms of disparity. We found that when blur is added to the background of the image, the viewer can perceive larger depth comparing to the images without any blur in the background. The increase of perceived depth can be considered as a function of the relative distance between the foreground and background, while it is insensitive to the distance between the viewer and the depth plane at which the blur is added.
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Beitrag (Sammelband oder Tagungsband)

  • Y. Pitrey
  • U. Engelke
  • Marcus Barkowsky
  • R. Pépion
  • P. Le Callet

Aligning Subjective Tests using a Low Cost Common Set

Lisbon, Portugal

  • (2011)

Abstract anzeigen

In this paper we use a common set between three subjective tests to build a linear mapping of the results of two tests onto the scale of one test identi ed as the reference test. We present our low-cost approach for the design of the common set and discuss the choice of the reference test. The mapping is then used to merge the outcomes of the three tests and provide an interesting comparison of the impact of coding artifacts, transmission errors and error-concealment in the context of Scalable Video Coding.
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Beitrag (Sammelband oder Tagungsband)

  • N. Staelens
  • I. Sedano
  • Marcus Barkowsky
  • L. Janowski
  • K. Brunnström
  • P. Le Callet

Standardized Toolchain And Model Development For Video Quality Assessment ‐ The Mission Of The Joint Effort Group In Vqeg

pg. 61.

Mechelen, Belgique

  • (2011)

Abstract anzeigen

Since 1997, the Video Quality Experts Group (VQEG) has been active in the field of subjective and objective video quality assessment. The group has validated competitive quality metrics throughout several projects. Each of these projects requires mandatory actions such as creating a testplan and obtaining databases consisting of degraded video sequences with corresponding subjective quality ratings. Recently, VQEG started a new open initiative, the Joint Effort Group (JEG), for encouraging joint collaboration on all mandatory actions needed to validate video quality metrics. Within the JEG, effort is made to advance the field of both subjective and objective video quality measurement by providing proper software tools and subjective databases to the community. One of the subprojects of the JEG is the joint development of a hybrid H.264/AVC objective quality metric. In this paper, we introduce the JEG and provide an overview of the different ongoing activities within this newly started group.
  • Angewandte Informatik
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Beitrag (Sammelband oder Tagungsband)

  • Y. Pitrey
  • Marcus Barkowsky
  • P. Le Callet
  • R. Pépion

Subjective Quality Assessment Of MPEG-4 Scalable Video Coding In a Mobile Scenario

pg. 72.

Paris, France

  • (2010)

Abstract anzeigen

Scalable Video Coding provides several levels of video encapsulated in a single video stream. In a transmission scenario such as broadcasting, this structure is quite advantageous as it can be used to address heterogeneous decoding targets with variable needs and requirements. However, this adaptability comes at a slight cost in coding efficiency when compared to single-layer coding. Based on subjective experiments, this cost is evaluated in this paper by comparing the new MPEG-4 Scalable Video Coding (SVC) standard with the now-established MPEG-4 AVC standard. Two scenarios are analyzed in the context of mobile transmission applications. The first scenario uses the same bitrate for SVC and AVC, leading to a slightly lower PSNR for SVC. The second scenario uses the same PSNR for SVC and AVC, leading to a slightly lower bitrate for AVC. The results of the subjective tests illustrate several interesting aspects of the relation between the performance of the two standards. First, we observe that the offset between AVC and SVC is not severe, though statistically significant in terms of user Mean Opinion Score (MOS) in such a context. Second, while adding another layer to SVC always leads to a performance loss, the impact of this loss decreases when the number of layers increases.
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Beitrag (Sammelband oder Tagungsband)

  • U. Engelke
  • Marcus Barkowsky
  • P. Le Callet
  • H.-J. Zepernick

Modelling Saliency Awareness for Objective Video Quality Assessment

Trondheim, Norway

  • (2010)

Abstract anzeigen

Existing video quality metrics do usually not take into consideration that spatial regions in video frames are of varying saliency and thus, differently attract the viewer\textquoterights attention. This paper proposes a model of saliency awareness to complement existing video quality metrics, with the aim to improve the agreement of objectively predicted quality with subjectively rated quality. For this purpose, we conducted a subjective experiment in which human observers rated the annoyance of videos with transmission distortions appearing either in a salient region or in a non-salient region. The mean opinion scores confirm that distortions in salient regions are perceived much more annoying. It is shown that application of the saliency awareness model to two video quality metrics considerably improves their quality prediction performance.
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Beitrag (Sammelband oder Tagungsband)

  • Marcus Barkowsky
  • P. Campisi
  • P. Le Callet
  • V. Rizzo

Crosstalk measurement and mitigation for autostereoscopic displays

pg. 7526-7531.

  • (2010)

Abstract anzeigen

In this paper we address the problem of crosstalk reduction for autostereoscopic displays. Crosstalk refers to the perception of one or more unwanted views in addition to the desired one. Specifically, the proposed approach consists of three different stages: a crosstalk measurement stage, where the crosstalk is modeled, a filter design stage, based on the results obtained out of the measurements, to mitigate the crosstalk effect, and a validation test carried out by means of subjective measurements performed in a controlled environment as recommended in ITU BT 500-11. Our analysis, synthesis, and subjective experiments are performed on the Alioscopy® display, which is a lenticular multiview display.
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Beitrag (Sammelband oder Tagungsband)

  • Marcus Barkowsky
  • K. Wang
  • R. Cousseau
  • K. Brunnström
  • R. Olsson
  • P. Le Callet

Subjective Quality Assessment of Error Concealment Strategies for 3DTV in the presence of asymmetric Transmission Errors

  • (2010)

Abstract anzeigen

The transmission of 3DTV sequences over packet based networks may result in degradations of the video quality due to packet loss. In the conventional 2D case, several different strategies are known for extrapolating the missing information and thus concealing the error. In 3D however, the residual error after concealment of one view might leads to binocular rivalry with the correctly received second view. In this paper, three simple alternatives are presented: frame freezing, a reduced playback speed, and displaying only a single view for both eyes, thus effectively switching to 2D presentation. In a subjective experiment the performance in terms of quality of experience of the three methods is evaluated for different packet loss scenarios. Error-free encoded videos at different bit rates have been included as anchor conditions. The subjective experiment method contains special precautions for measuring the Quality of Experience (QoE) for 3D content and also contains an indicator for visual discomfort. The results indicate that switching to 2D is currently the best choice but difficulties with visual discomfort should be expected even for this method.
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Beitrag (Sammelband oder Tagungsband)

  • Y. Pitrey
  • Marcus Barkowsky
  • P. Le Callet
  • R. Pépion

Evaluation of MPEG4-SVC for QoE Protection in the Context of Transmission Errors

San Diego, CA, USA

  • (2010)

Abstract anzeigen

Scalable Video Coding (SVC) provides a way to encapsulate several video layers with increasing quality and resolution in a single bitstream. Thus it is particularly adapted to address heterogeneous networks and a wide variety of decoding devices. In this paper, we evaluate the interest of SVC in a different context, which is error concealment after transmission on networks subject to packet loss. The encoded scalable video streams contain two layers with different spatial and temporal resolutions designed for mobile video communications with medium size and average to low bitrates. The main idea is to use the base layer to conceal errors in the higher layers if they are corrupted or lost. The base layer is first upscaled either spatially or temporally to reach the same resolution as the layer to conceal. Two error-concealment techniques using the base layer are then proposed for the MPEG-4 SVC standard, involving frame-level concealment and pixel-level concealment. These techniques are compared to the upscaled base layer as well as to a classical single-layer MPEG- 4 AVC/H.264 error-concealment technique. The comparison is carried out through a subjective experiment, in order to evaluate the Quality-of-Experience of the proposed techniques. We study several scenarios involving various bitrates and resolutions for the base layer of the SVC streams. The results show that SVC-based error concealment can provide significantly higher visual quality than single-layer-based techniques. Moreover, we demonstrate that the resolution and bitrate of the base layer have a strong impact on the perceived quality of the concealment.
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Beitrag (Sammelband oder Tagungsband)

  • W. Chen
  • J. Fournier
  • Marcus Barkowsky
  • P. Le Callet

New Requirements of Subjective Video Quality Assessment Methodologies for 3DTV

  • (2010)

Abstract anzeigen

In this paper, the new challenges of 3DTV for subjective assessment are discussed. Conventional 2D methods have severe limitations which will be revealed. Based on the understanding of the new characteristics brought by 3DTV, changes and additions in the requirements for subjective assessment are proposed in order to develop a novel subjective video quality assessment methodology for 3DTV. In particular, depth rendering for 3D display is selected to give a further discussion. The depth rendering abilities are defined as a combination of the physical parameters and the perceptual constrains. We analyze different types of stereoscopic and multiview displays. Several problems regarding depth rendering are discussed in order to highlight the diversity and complexity of assessing 3DTV.
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Beitrag (Sammelband oder Tagungsband)

  • Marcus Barkowsky
  • P. Le Callet

The influence of autostereoscopic 3D displays on subsequent task performance

pg. 7524-7534.

  • (2010)

Abstract anzeigen

Viewing 3D content on an autostereoscopic is an exciting experience. This is partly due to the fact that the 3D effect is seen without glasses. Nevertheless, it is an unnatural condition for the eyes as the depth effect is created by the disparity of the left and the right view on a flat screen instead of having a real object at the corresponding location. Thus, it may be more tiring to watch 3D than 2D. This question is investigated in this contribution by a subjective experiment. A search task experiment is conducted and the behavior of the participants is recorded with an eyetracker. Several indicators both for low level perception as well as for the task performance itself are evaluated. In addition two optometric tests are performed. A verification session with conventional 2D viewing is included. The results are discussed in detail and it can be concluded that the 3D viewing does not have a negative impact on the task performance used in the experiment.
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Beitrag (Sammelband oder Tagungsband)

  • Marcus Barkowsky
  • M. Pinson
  • R. Pépion
  • P. Le Callet

Analysis of Freely Available Dataset for HDTV including Coding and Transmission Distortions

  • (2010)

Abstract anzeigen

We present the design, preparation, and analysis of a subjective experiment on typical HDTV sequences and scenarios. This experiment follows the guidelines of ITU and VQEG in order to obtain reproducible results. The careful selection of content and distortions extend over a wide and realistic range of typical transmission scenarios. Detailed statistical analysis provides important insight into the relationship between technical parameters of encoding, transmission and decoding and subjectively perceived video quality.
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Zeitschriftenartikel

  • Marcus Barkowsky
  • J. Bialkowski
  • B. Eskofier
  • R. Bitto
  • A. Kaup

Temporal Trajectory Aware Video Quality Measure

In: IEEE Journal of Selected Topics in Signal Processing vol. 3 pg. 266-279.

IEEE

  • (2009)

Abstract anzeigen

The measurement of video quality for lossy and low-bitrate network transmissions is a challenging topic. Especially, the temporal artifacts which are introduced by video transmission systems and their effects on the viewer's satisfaction have to be addressed. This paper focuses on a framework that adds a temporal distortion awareness to typical video quality measurement algorithms. A motion estimation is used to track image areas over time. Based on the motion vectors and the motion prediction error, the appearance of new image areas and the display time of objects is evaluated. Additionally, degradations which stick to moving objects can be judged more exactly. An implementation of this framework for multimedia sequences, e.g., QCIF, CIF, or VGA resolution, is presented in detail. It shows that the processing steps and the signal representations that are generated by the algorithm follow the reasoning of a human observer in a subjective experiment. The improvements that can be achieved with the newly proposed algorithm are demonstrated using the results of the Multimedia Phase I database of the Video Quality Experts Group.
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Beitrag (Sammelband oder Tagungsband)

  • Marcus Barkowsky
  • R. Cousseau
  • P. Le Callet

Influence of Depth Rendering on the Quality of Experience for an Autostereoscopic Display

San Diego, California, U.S.A.

  • (2009)

Abstract anzeigen

Autostereoscopic displays simplify the presentation of 3D content because they do not require any glasses and they allow the perception of motion parallax. While the perception of depth is certainly an added value, the technical rendering process of the current display technology also introduces artifacts. For the viewer, the tradeoff may be expressed in terms of quality of experience. However, quality of experience assessment related to 3D is still an open issue. Towards this goal, several original subjective test methods are proposed and compared that are meant for assessing the quality of experience. A split-screen setup simultaneously displays a 2D and a 3D presentation. The observers vote according to their preference in terms of quality of experience. In four experiments, the influence of the depth rendering process is evaluated. The results indicate that the degradation by the depth rendering process may easily dominate the added value of depth in a content specific manner.
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Beitrag (Sammelband oder Tagungsband)

  • Marcus Barkowsky
  • B. Eskofier
  • R. Bitto
  • J. Bialkowski
  • A. Kaup

Perceptually motivated spatial and temporal integration of pixel based video quality measures

pg. 1-7.

Association for Computer Machinery, ACM

  • (2007)

Abstract anzeigen

In the evaluation of video quality often a full reference approach is used, thus calculating some measure of difference between the reference frames and the distorted frames. Often this measure returns one value per pixel, in the simplest case the squared difference. Conventionally, this pixel based measure is averaged over space and time. This paper introduces a psychophysically derived algorithm for this step. It uses the distribution of the cells in the fovea and the assumption that in a subjective test the part with the highest distortion is most important. Additionally, a temporal integration step is proposed which models the recency and forgiveness effect. Different video quality measures are enhanced with these two steps and their performance is evaluated using the results of a subjective test.
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Beitrag (Sammelband oder Tagungsband)

  • Marcus Barkowsky
  • J. Bialkowski
  • R. Bitto
  • A. Kaup

Temporal Registration using 3D Phase Correlation and a Maximum Likelihood Approach in the Perceptual Evaluation of Video Quality

pg. 195-198.

  • (2007)

Abstract anzeigen

The estimation of the video quality is often performed using a full reference approach. One of the most important steps in a video quality measurement algorithm is to find the corresponding frames between the reference and the distorted video sequence. In this paper an algorithm with three steps is proposed. First, an extended version of the phase correlation is used to find candidate images with an arbitrary temporal offset, spatial scaling or spatial shift. Based on the assumption that the spatial scaling and spatial shift does not change during the sequence a set of probable parameters is selected. Finally, a maximum likelihood estimation is applied to select those temporal offsets which support the smoothest playback. A set of video sequences degraded with several distortions which are typical for multimedia scenarios are used to compare the performance to other algorithms.
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Zeitschriftenartikel

  • J. Bialkowski
  • Marcus Barkowsky
  • A. Kaup

Fast Video Transcoding from H.263 To H. 264/AVC

In: Multimedia Tools and Applications vol. 35 pg. 127-146.

Springer

  • (2007)

DOI: 10.1007/s11042-007-0126-7

Abstract anzeigen

In the past 10 years detailed works on different video transcoders have been published. However, the new ITU-T Recommendation H.264—also adapted as ISO/IEC MPEG-4 Part 10 (AVC)—provides many new encoding options for the prediction processes that lead to difficulties for low complexity transcoding. In this work we present very fast transcoding techniques to convert H.263 bitstreams into H.264/AVC bitstreams. We will give reasoning, why the proposed pixel domain approach is advantageous in this scenario instead of using a DCT domain transcoder. Our approach results in less than 9% higher data rate at equivalent PSNR quality compared to a full-search approach. But this rate loss allows the reduction of the search complexity by a factor of over 200 for inter frames and still a reduction of over 70% for intra frames. A comparison to a fast search algorithm is given. We also provide simulation results that our algorithm works for transcoding MPEG-2 to H.264/AVC in the aimed scenario.
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Beitrag (Sammelband oder Tagungsband)

  • Marcus Barkowsky
  • B. Eskofier
  • J. Bialkowski
  • A. Kaup

Influence of the Presentation Time on Subjective Votings of Coded Still Images

pg. 429-432.

IEEE Atlanta

  • (2006)

Abstract anzeigen

The quality of coded images is often assessed by a subjective test. Usually the viewers get as much time as they need to find a stable result. In video sequences however, the viewer has to judge the quality in a shorter time that is defined by the changing content or a following scene cut. Therefore it is desirable to know the influence of a shorter presentation time on the perceptibility of distortions. In this paper we present the results of a suitable subjective test on coded still images. The images were presented for six different durations, ranging from 200 ms to 3 s. Special care was taken to avoid the memorization effect usually present after short presentations. The results show that the viewers tend to avoid extreme votings at short durations. The variance of the votings is also discussed in detail. Based on the result of the voting for the longest presentation time, we propose a prediction model for the voting of the shorter durations using a logistic curve fit. This presentation time model (PTM) is presented and analysed in detail.
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Beitrag (Sammelband oder Tagungsband)

  • J. Bialkowski
  • Marcus Barkowsky
  • A. Kaup

A new algorithm for reducing the requantization loss in video transcoding

pg. 1-5.

  • (2006)

Abstract anzeigen

Video transcoders are devices that convert one video bitstream into another type of bitstream, either with or without standard format conversion. One step to be applied in video transcoders is the requantization of the transform coefficients, if an adaptation to a lower data rate is necessary. During this step, the quality is in most cases degraded compared to a single quantization. This is a consequence of nonoverlapping quantization characteristics of the input and the output quantizer. In this work we propose a new choice of the reconstruction level for the requantization step depending on the effective quantization curve of both quantization parameters involved. The reconstruction level is calculated such that it is centered in each effective quantization interval after requantization. Compared to the standard midpoint requantization this leads to quality gains of 3 dB PSNR for most pairs of input and output quantization parameters (QP). The algorithm is useful for intra- and inter-frame coding.
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Beitrag (Sammelband oder Tagungsband)

  • U. Fecker
  • Marcus Barkowsky
  • A. Kaup

Improving the Prediction Efficiency for Multi-View Video Coding Using Histogram Matching

[Isernhagen]

  • (2006)

Abstract anzeigen

Applications for video data recorded witha setup of several cameras are currently attracting increasinginterest. For such multi-view sequences, efficientcoding is crucial to handle the enormous amountof data. However, significant luminance and chrominancevariations between the different views, which oftenoriginate from imperfect camera calibration, areable to reduce the coding efficiency and the renderingquality. In this paper, we suggest the usage of histogrammatching to compensate these differences in apre-filtering step. After a description of the proposedalgorithm, it is explained how histogram matching canbe applied to multi-view video data. The effect of histogrammatching on the coding performance is evaluatedby statistically analysing prediction from temporalas well as from spatial references. For several testsequences, results are shown which indicate that theamount of spatial prediction across different cameraviews can be increased by applying histogram matching.
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Beitrag (Sammelband oder Tagungsband)

  • Marcus Barkowsky
  • J. Bialkowski
  • A. Kaup

Subjektiver Videobetrachtungstest für niederratige Multimedia-Szenarien

pg. 169-175.

  • (2005)
  • Angewandte Informatik
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Beitrag (Sammelband oder Tagungsband)

  • J. Bialkowski
  • M. Menden
  • Marcus Barkowsky
  • A. Kaup

A Fast H.263 to H.264 Inter-Frame Transcoder with Motion Vector Refinement

pg. 47-52.

San Francisco

  • (2004)

Abstract anzeigen

Video transcoding techniques supply interoperability of a great variety of devices that can be connected by various communication networks with different data rate requirements. Particularly inhomogeneous video transcoding is the conversion of an existing video bitstream from one standard into a bitstream of another standard, for example the conversion from H.263 data into H.264 data. It may also include parameter adaptations such as bitrate or frame rate reduction. In this work, we present a low-complexity transcoder design for transcoding Interframe macroblocks from H.263 to H.264. The large complexity reduction comes from reusing motion vectors of the input bitstream and from the fact that only a subset of all possible H.264 coding parameters is used. The selection of these parameters is based on statistical investigations of encoded H.264 parameters from a full parameter search on decoded H.263 sequences. Our approach leads to small rate-distortion losses compared to the full parameter encoder below 0.5 dB at comparable data rates, but the computational complexity reduction is over 98% for finding a suitable macroblock decision. Compared to simply copying the motion vectors without post-processing, the rate-distortion gain of our approach is up to 2 dB at equivalent rate.
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