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href="/wiki/Video_quality" title="Video quality">video quality</a> as experienced by humans. It is concerned with how video is perceived by a viewer (also called "observer" or "subject") and designates their opinion on a particular <a href="/wiki/Video" title="Video">video</a> sequence. It is related to the field of <a href="/wiki/Quality_of_experience" title="Quality of experience">Quality of Experience</a>. Measuring subjective video quality is necessary because objective quality assessment algorithms such as <a href="/wiki/PSNR" class="mw-redirect" title="PSNR">PSNR</a> have been shown to correlate poorly with subjective ratings. Subjective ratings may also be used as ground truth to develop new algorithms. </p><p><b>Subjective video quality tests</b> are <a href="/wiki/Psychophysics" title="Psychophysics">psychophysical experiments</a> in which a number of viewers rate a given set of stimuli. These tests are quite expensive in terms of time (preparation and running) and human resources and must therefore be carefully designed. </p><p>In subjective video quality tests, typically, <b>SRCs</b> ("Sources", i.e. original video sequences) are treated with various conditions (<b>HRCs</b> for "Hypothetical Reference Circuits") to generate <b>PVSs</b> ("Processed Video Sequences").<sup id="cite_ref-1" class="reference"><a href="#cite_note-1"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup> </p> <meta property="mw:PageProp/toc" /> <div class="mw-heading mw-heading2"><h2 id="Measurement">Measurement</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Subjective_video_quality&action=edit&section=1" title="Edit section: Measurement"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>The main idea of measuring subjective video quality is similar to the <a href="/wiki/Mean_opinion_score" title="Mean opinion score">mean opinion score</a> (MOS) evaluation for <a href="/wiki/Sound" title="Sound">audio</a>. To evaluate the subjective video quality of a video processing system, the following steps are typically taken: </p> <ul><li>Choose original, unimpaired video sequences for testing</li> <li>Choose settings of the system that should be evaluated</li> <li>Apply settings to the SRC, which results in the test sequences</li> <li>Choose a test method, describing how sequences are presented to viewers and how their opinion is collected</li> <li>Invite a panel of viewers</li> <li>Carry out testing in a specific environment (e.g. a laboratory context) and present each PVS in a certain order to every viewer</li> <li>Calculate rating results for individual PVSs, SRCs and HRCs, e.g. the <a href="/wiki/Mean_opinion_score" title="Mean opinion score">MOS</a></li></ul> <p>Many parameters of the viewing conditions may influence the results, such as room illumination, display type, brightness, contrast, resolution, viewing distance, and the age and educational level of viewers. It is therefore advised to report this information along with the obtained ratings. </p> <div class="mw-heading mw-heading3"><h3 id="Source_selection">Source selection</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Subjective_video_quality&action=edit&section=2" title="Edit section: Source selection"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Typically, a system should be tested with a representative number of different contents and content characteristics. For example, one may select excerpts from contents of different genres, such as action movies, news shows, and cartoons. The length of the source video depends on the purpose of the test, but typically, sequences of no less than 10 seconds are used. </p><p>The amount of motion and spatial detail should also cover a broad range. This ensures that the test contains sequences which are of different complexity. </p><p>Sources should be of pristine quality. There should be no visible <a href="/wiki/Compression_artifact" title="Compression artifact">coding artifacts</a> or other properties that would lower the quality of the original sequence. </p> <div class="mw-heading mw-heading3"><h3 id="Settings">Settings</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Subjective_video_quality&action=edit&section=3" title="Edit section: Settings"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>The design of the HRCs depends on the system under study. Typically, multiple independent variables are introduced at this stage, and they are varied with a number of levels. For example, to test the quality of a <a href="/wiki/Video_codec" title="Video codec">video codec</a>, independent variables may be the video encoding software, a target bitrate, and the target resolution of the processed sequence. </p><p>It is advised to select settings that result in ratings which cover the full quality range. In other words, assuming an <a href="/wiki/Absolute_Category_Rating" title="Absolute Category Rating">Absolute Category Rating</a> scale, the test should show sequences that viewers would rate from bad to excellent. </p> <div class="mw-heading mw-heading3"><h3 id="Viewers">Viewers</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Subjective_video_quality&action=edit&section=4" title="Edit section: Viewers"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <div class="mw-heading mw-heading4"><h4 id="Number_of_viewers">Number of viewers</h4><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Subjective_video_quality&action=edit&section=5" title="Edit section: Number of viewers"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Viewers are also called "observers" or "subjects". A certain minimum number of viewers should be invited to a study, since a larger number of subjects increases the reliability of the experiment outcome, for example by reducing the standard deviation of averaged ratings. Furthermore, there is a risk of having to exclude subjects for unreliable behavior during rating. </p><p>The minimum number of subjects that are required for a subjective video quality study is not strictly defined. According to ITU-T, any number between 4 and 40 is possible, where 4 is the absolute minimum for statistical reasons, and inviting more than 40 subjects has no added value. In general, at least 15 observers should participate in the experiment. They should not be directly involved in picture quality evaluation as part of their work and should not be experienced assessors.<sup id="cite_ref-:1_2-0" class="reference"><a href="#cite_note-:1-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup> In other documents, it is also claimed that at minimum 10 subjects are needed to obtain meaningful averaged ratings.<sup id="cite_ref-3" class="reference"><a href="#cite_note-3"><span class="cite-bracket">[</span>3<span class="cite-bracket">]</span></a></sup> </p><p>However, most recommendations for the number of subjects have been designed for measuring video quality encountered by a home television or PC user, where the range and diversity of distortions tend to be limited (e.g., to encoding artifacts only). Given the large ranges and diversity of impairments that may occur on videos captured with mobile devices and/or transmitted over wireless networks, generally, a larger number of human subjects may be required. </p><p>Brunnström and Barkowsky have provided calculations for estimating the minimum number of subjects necessary based on existing subjective tests.<sup id="cite_ref-4" class="reference"><a href="#cite_note-4"><span class="cite-bracket">[</span>4<span class="cite-bracket">]</span></a></sup> They claim that in order to ensure statistically significant differences when comparing ratings, a larger number of subjects than usually recommended may be needed. </p> <div class="mw-heading mw-heading4"><h4 id="Viewer_selection">Viewer selection</h4><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Subjective_video_quality&action=edit&section=6" title="Edit section: Viewer selection"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Viewers should be non-experts in the sense of not being professionals in the field of video coding or related domains. This requirement is introduced to avoid potential subject bias.<sup id="cite_ref-:1_2-1" class="reference"><a href="#cite_note-:1-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup> </p><p>Typically, viewers are screened for <a href="/wiki/Normal_vision" class="mw-redirect" title="Normal vision">normal vision</a> or corrected-to-normal vision using <a href="/wiki/Snellen_chart" title="Snellen chart">Snellen charts</a>. <a href="/wiki/Color_blindness" title="Color blindness">Color blindness</a> is often tested with <a href="/wiki/Ishihara_test" title="Ishihara test">Ishihara plates</a>.<sup id="cite_ref-:1_2-2" class="reference"><a href="#cite_note-:1-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup> </p><p>There is an ongoing discussion in the <a href="/wiki/Quality_of_experience" title="Quality of experience">QoE</a> community as to whether a viewer's cultural, social, or economic background has a significant impact on the obtained subjective video quality results. A systematic study involving six laboratories in four countries found no statistically significant impact of subject's language and culture / country of origin on video quality ratings.<sup id="cite_ref-:3_5-0" class="reference"><a href="#cite_note-:3-5"><span class="cite-bracket">[</span>5<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading3"><h3 id="Test_environment">Test environment</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Subjective_video_quality&action=edit&section=7" title="Edit section: Test environment"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Subjective quality tests can be done in any environment. However, due to possible influence factors from heterogenous contexts, it is typically advised to perform tests in a neutral environment, such as a dedicated laboratory room. Such a room may be sound-proofed, with walls painted in neutral grey, and using properly calibrated light sources. Several recommendations specify these conditions.<sup id="cite_ref-:2_6-0" class="reference"><a href="#cite_note-:2-6"><span class="cite-bracket">[</span>6<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-:0_7-0" class="reference"><a href="#cite_note-:0-7"><span class="cite-bracket">[</span>7<span class="cite-bracket">]</span></a></sup> Controlled environments have been shown to result in lower variability in the obtained scores.<sup id="cite_ref-:3_5-1" class="reference"><a href="#cite_note-:3-5"><span class="cite-bracket">[</span>5<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading4"><h4 id="Crowdsourcing">Crowdsourcing</h4><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Subjective_video_quality&action=edit&section=8" title="Edit section: Crowdsourcing"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p><a href="/wiki/Crowdsourcing" title="Crowdsourcing">Crowdsourcing</a> has recently been used for subjective video quality evaluation, and more generally, in the context of <a href="/wiki/Quality_of_Experience" class="mw-redirect" title="Quality of Experience">Quality of Experience</a>.<sup id="cite_ref-8" class="reference"><a href="#cite_note-8"><span class="cite-bracket">[</span>8<span class="cite-bracket">]</span></a></sup> Here, viewers give ratings using their own computer, at home, rather than taking part in a subjective quality test in laboratory rooms. While this method allows for obtaining more results than in traditional subjective tests at lower costs, the validity and reliability of the gathered responses must be carefully checked.<sup id="cite_ref-9" class="reference"><a href="#cite_note-9"><span class="cite-bracket">[</span>9<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading3"><h3 id="Analysis_of_results">Analysis of results</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Subjective_video_quality&action=edit&section=9" title="Edit section: Analysis of results"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Opinions of viewers are typically averaged into the mean opinion score (MOS). To this aim, the labels of categorical scales may be translated into numbers. For example, the responses "bad" to "excellent" can be mapped to the values 1 to 5, and then averaged. MOS values should always be reported with their statistical <a href="/wiki/Confidence_interval" title="Confidence interval">confidence intervals</a> so that the general agreement between observers can be evaluated. </p> <div class="mw-heading mw-heading4"><h4 id="Subject_screening">Subject screening</h4><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Subjective_video_quality&action=edit&section=10" title="Edit section: Subject screening"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Often, additional measures are taken before evaluating the results. Subject screening is a process in which viewers whose ratings are considered invalid or unreliable are rejected from further analysis. Invalid ratings are hard to detect, as subjects may have rated without looking at a video, or cheat during the test. The overall reliability of a subject can be determined by various procedures, some of which are outlined in ITU-R and ITU-T recommendations.<sup id="cite_ref-:1_2-3" class="reference"><a href="#cite_note-:1-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-:0_7-1" class="reference"><a href="#cite_note-:0-7"><span class="cite-bracket">[</span>7<span class="cite-bracket">]</span></a></sup> For example, the correlation between a person's individual scores and the overall MOS, evaluated for all sequences, is a good indicator of their reliability in comparison with the remaining test participants. </p> <div class="mw-heading mw-heading5"><h5 id="Advanced_models">Advanced models</h5><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Subjective_video_quality&action=edit&section=11" title="Edit section: Advanced models"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>While rating stimuli, humans are subject to biases. These may lead to different and inaccurate scoring behavior and consequently result in MOS values that are not representative of the “true quality” of a stimulus. In the recent years, advanced models have been proposed that aim at formally describing the rating process and subsequently recovering noisiness in subjective ratings. According to Janowski et al., subjects may have an opinion bias that generally shifts their scores, as well as a scoring imprecision that is dependent on the subject and stimulus to be rated.<sup id="cite_ref-10" class="reference"><a href="#cite_note-10"><span class="cite-bracket">[</span>10<span class="cite-bracket">]</span></a></sup> Li et al. have proposed to differentiate between <i>subject inconsistency</i> and <i>content ambiguity</i>.<sup id="cite_ref-11" class="reference"><a href="#cite_note-11"><span class="cite-bracket">[</span>11<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading2"><h2 id="Standardized_testing_methods">Standardized testing methods</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Subjective_video_quality&action=edit&section=12" title="Edit section: Standardized testing methods"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>There are many ways to select proper sequences, system settings, and test methodologies. A few of them have been standardized. They are thoroughly described in several ITU-R and ITU-T recommendations, among those ITU-R BT.500<sup id="cite_ref-:0_7-2" class="reference"><a href="#cite_note-:0-7"><span class="cite-bracket">[</span>7<span class="cite-bracket">]</span></a></sup> and ITU-T P.910.<sup id="cite_ref-:1_2-4" class="reference"><a href="#cite_note-:1-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup> While there is an overlap in certain aspects, the BT.500 recommendation has its roots in broadcasting, whereas P.910 focuses on multimedia content. </p><p>A standardized testing method usually describes the following aspects: </p> <ul><li>how long an experiment session lasts</li> <li>where the experiment takes place</li> <li>how many times and in which order each PVS should be viewed</li> <li>whether ratings are taken once per stimulus (e.g. after presentation) or continuously</li> <li>whether ratings are absolute, i.e. referring to one stimulus only, or relative (comparing two or more stimuli)</li> <li>which scale ratings are taken on</li></ul> <p>Another recommendation, ITU-T P.913,<sup id="cite_ref-:2_6-1" class="reference"><a href="#cite_note-:2-6"><span class="cite-bracket">[</span>6<span class="cite-bracket">]</span></a></sup> gives researchers more freedom to conduct subjective quality tests in environments different from a typical testing laboratory, while still requiring them to report all details necessary to make such tests reproducible. </p> <div class="mw-heading mw-heading3"><h3 id="Examples">Examples</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Subjective_video_quality&action=edit&section=13" title="Edit section: Examples"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Below, some examples of standardized testing procedures are explained. </p> <div class="mw-heading mw-heading4"><h4 id="Single-Stimulus">Single-Stimulus</h4><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Subjective_video_quality&action=edit&section=14" title="Edit section: Single-Stimulus"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <ul><li><b>ACR </b>(Absolute Category Rating):<sup id="cite_ref-:1_2-5" class="reference"><a href="#cite_note-:1-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup> each sequence is rated individually on the <i>ACR scale</i>. The labels on the scale are "bad", "poor", "fair", "good", and "excellent", and they are translated to the values 1, 2, 3, 4 and 5 when calculating the MOS.</li> <li><b>ACR-HR</b> (Absolute Category Rating with Hidden Reference): a variation of ACR, in which an original unimpaired source sequence is shown in addition to the impaired sequences, without informing the subjects of its presence (hence, "hidden"). The ratings are calculated as differential scores between the reference and the impaired versions. The differential score is defined as the score of the PVS minus the score given to the hidden reference, plus the number of points on the scale. For example, if a PVS is rated as “poor", and its corresponding hidden reference as “good", then the rating is <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\textstyle 2-4+5=3}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="false" scriptlevel="0"> <mn>2</mn> <mo>−</mo> <mn>4</mn> <mo>+</mo> <mn>5</mn> <mo>=</mo> <mn>3</mn> </mstyle> </mrow> <annotation encoding="application/x-tex">{\textstyle 2-4+5=3}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/df46f47051e5bfec252c9bcecdb0fabd22c3a32d" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.505ex; width:13.429ex; height:2.343ex;" alt="{\textstyle 2-4+5=3}"></span>. When these ratings are averaged, the result is not a MOS, but a differential MOS ("DMOS").</li> <li><b>SSCQE</b> (Single Stimulus Continuous Quality Rating):<sup id="cite_ref-:0_7-3" class="reference"><a href="#cite_note-:0-7"><span class="cite-bracket">[</span>7<span class="cite-bracket">]</span></a></sup> a longer sequence is rated continuously over time using a slider device (a variation of a <a href="/wiki/Fade_(audio_engineering)" title="Fade (audio engineering)">fader</a>), on which subjects rate the current quality. Samples are taken in regular intervals, resulting in a quality curve over time rather than a single quality rating.</li></ul> <div class="mw-heading mw-heading4"><h4 id="Double-stimulus_or_multiple_stimulus">Double-stimulus or multiple stimulus</h4><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Subjective_video_quality&action=edit&section=15" title="Edit section: Double-stimulus or multiple stimulus"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <ul><li><b>DSCQS</b> (Double Stimulus Continuous Quality Scale):<sup id="cite_ref-:0_7-4" class="reference"><a href="#cite_note-:0-7"><span class="cite-bracket">[</span>7<span class="cite-bracket">]</span></a></sup> the viewer sees an unimpaired reference and the impaired sequence in a random order. They are allowed to re-view the sequences, and then rate the quality for both on a continuous scale labeled with the ACR categories.</li> <li><b>DSIS</b> (Double Stimulus Impairment Scale)<sup id="cite_ref-:0_7-5" class="reference"><a href="#cite_note-:0-7"><span class="cite-bracket">[</span>7<span class="cite-bracket">]</span></a></sup> and <b>DCR</b> (Degradation Category Rating):<sup id="cite_ref-:1_2-6" class="reference"><a href="#cite_note-:1-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup> both refer to the same method. The viewer sees an unimpaired reference video, then the same video impaired, and after that they are asked to vote on the second video using a so-called <i>impairment scale</i> (from "impairments are imperceptible" to "impairments are very annoying").</li> <li><b>PC</b> (Pair Comparison):<sup id="cite_ref-:1_2-7" class="reference"><a href="#cite_note-:1-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup> instead of comparing an unimpaired and impaired sequence, different impairment types (HRCs) are compared. All possible combinations of HRCs should be evaluated.</li></ul> <div class="mw-heading mw-heading3"><h3 id="Choice_of_methodology">Choice of methodology</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Subjective_video_quality&action=edit&section=16" title="Edit section: Choice of methodology"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Which method to choose largely depends on the purpose of the test and possible constraints in time and other resources. Some methods may have fewer context effects (i.e. where the order of stimuli influences the results), which are unwanted test biases.<sup id="cite_ref-12" class="reference"><a href="#cite_note-12"><span class="cite-bracket">[</span>12<span class="cite-bracket">]</span></a></sup> In ITU-T P.910, it is noted that methods such as DCR should be used for testing the fidelity of transmission, especially in high quality systems. ACR and ACR-HR are better suited for qualification tests and – due to giving absolute results – comparison of systems. The PC method has a high discriminatory power, but it requires longer test sessions. </p> <div class="mw-heading mw-heading2"><h2 id="Databases">Databases</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Subjective_video_quality&action=edit&section=17" title="Edit section: Databases"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>The results of subjective quality tests, including the used stimuli, are called <b>databases</b>. A number of subjective picture and video quality databases based on such studies have been made publicly available by research institutes. These databases – some of which have become de facto standards – are used globally by television, cinematic, and video engineers around the world to design and test objective quality models, since the developed models can be trained against the obtained subjective data. An overview of publicly available databases has been compiled by the <a rel="nofollow" class="external text" href="https://vqeg.org/video-datasets-and-organizations/">Video Quality Experts Group</a>, and video assets have been made available in the <a rel="nofollow" class="external text" href="https://cdvl.org/">Consumer Digital Video Library</a>. </p> <div class="mw-heading mw-heading2"><h2 id="References">References</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Subjective_video_quality&action=edit&section=18" title="Edit section: References"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <div class="mw-references-wrap mw-references-columns"><ol class="references"> <li id="cite_note-1"><span class="mw-cite-backlink"><b><a href="#cite_ref-1">^</a></b></span> <span class="reference-text"><a rel="nofollow" class="external text" href="http://www.itu.int/ITU-T/studygroups/com09/docs/tutorial_opavc.pdf">ITU-T Tutorial: Objective perceptual assessment of video quality: Full reference television</a>, 2004.</span> </li> <li id="cite_note-:1-2"><span class="mw-cite-backlink">^ <a href="#cite_ref-:1_2-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-:1_2-1"><sup><i><b>b</b></i></sup></a> <a href="#cite_ref-:1_2-2"><sup><i><b>c</b></i></sup></a> <a href="#cite_ref-:1_2-3"><sup><i><b>d</b></i></sup></a> <a href="#cite_ref-:1_2-4"><sup><i><b>e</b></i></sup></a> <a href="#cite_ref-:1_2-5"><sup><i><b>f</b></i></sup></a> <a href="#cite_ref-:1_2-6"><sup><i><b>g</b></i></sup></a> <a href="#cite_ref-:1_2-7"><sup><i><b>h</b></i></sup></a></span> <span class="reference-text"><a rel="nofollow" class="external text" href="https://www.itu.int/rec/T-REC-P.910/en">ITU-T Rec. P.910 : Subjective video quality assessment methods for multimedia applications</a>, 2008.</span> </li> <li id="cite_note-3"><span class="mw-cite-backlink"><b><a href="#cite_ref-3">^</a></b></span> <span class="reference-text">Winkler, Stefan. <a rel="nofollow" class="external text" href="http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.160.3958&rep=rep1&type=pdf">"On the properties of subjectiveratings in video quality experiments"</a>. <i>Proc.</i> <i>Quality of Multimedia Experience</i>, 2009.</span> </li> <li id="cite_note-4"><span class="mw-cite-backlink"><b><a href="#cite_ref-4">^</a></b></span> <span class="reference-text"><style data-mw-deduplicate="TemplateStyles:r1238218222">.mw-parser-output cite.citation{font-style:inherit;word-wrap:break-word}.mw-parser-output .citation q{quotes:"\"""\"""'""'"}.mw-parser-output .citation:target{background-color:rgba(0,127,255,0.133)}.mw-parser-output .id-lock-free.id-lock-free a{background:url("//upload.wikimedia.org/wikipedia/commons/6/65/Lock-green.svg")right 0.1em center/9px no-repeat}.mw-parser-output .id-lock-limited.id-lock-limited a,.mw-parser-output .id-lock-registration.id-lock-registration a{background:url("//upload.wikimedia.org/wikipedia/commons/d/d6/Lock-gray-alt-2.svg")right 0.1em center/9px no-repeat}.mw-parser-output .id-lock-subscription.id-lock-subscription a{background:url("//upload.wikimedia.org/wikipedia/commons/a/aa/Lock-red-alt-2.svg")right 0.1em center/9px no-repeat}.mw-parser-output .cs1-ws-icon a{background:url("//upload.wikimedia.org/wikipedia/commons/4/4c/Wikisource-logo.svg")right 0.1em center/12px no-repeat}body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-free a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-limited a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-registration a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-subscription a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .cs1-ws-icon a{background-size:contain;padding:0 1em 0 0}.mw-parser-output .cs1-code{color:inherit;background:inherit;border:none;padding:inherit}.mw-parser-output .cs1-hidden-error{display:none;color:var(--color-error,#d33)}.mw-parser-output .cs1-visible-error{color:var(--color-error,#d33)}.mw-parser-output .cs1-maint{display:none;color:#085;margin-left:0.3em}.mw-parser-output .cs1-kern-left{padding-left:0.2em}.mw-parser-output .cs1-kern-right{padding-right:0.2em}.mw-parser-output .citation .mw-selflink{font-weight:inherit}@media screen{.mw-parser-output .cs1-format{font-size:95%}html.skin-theme-clientpref-night .mw-parser-output .cs1-maint{color:#18911f}}@media screen and (prefers-color-scheme:dark){html.skin-theme-clientpref-os .mw-parser-output .cs1-maint{color:#18911f}}</style><cite id="CITEREFBrunnströmBarkowsky2018" class="citation journal cs1">Brunnström, Kjell; Barkowsky, Marcus (2018-09-25). <a rel="nofollow" class="external text" href="http://miun.diva-portal.org/smash/get/diva2:1251082/FULLTEXT01">"Statistical quality of experience analysis: on planning the sample size and statistical significance testing"</a>. <i>Journal of Electronic Imaging</i>. <b>27</b> (5): 053013. <a href="/wiki/Bibcode_(identifier)" class="mw-redirect" title="Bibcode (identifier)">Bibcode</a>:<a rel="nofollow" class="external text" href="https://ui.adsabs.harvard.edu/abs/2018JEI....27e3013B">2018JEI....27e3013B</a>. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1117%2F1.jei.27.5.053013">10.1117/1.jei.27.5.053013</a>. <a href="/wiki/ISSN_(identifier)" class="mw-redirect" title="ISSN (identifier)">ISSN</a> <a rel="nofollow" class="external text" href="https://search.worldcat.org/issn/1017-9909">1017-9909</a>. <a href="/wiki/S2CID_(identifier)" class="mw-redirect" title="S2CID (identifier)">S2CID</a> <a rel="nofollow" class="external text" href="https://api.semanticscholar.org/CorpusID:53058660">53058660</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Journal+of+Electronic+Imaging&rft.atitle=Statistical+quality+of+experience+analysis%3A+on+planning+the+sample+size+and+statistical+significance+testing&rft.volume=27&rft.issue=5&rft.pages=053013&rft.date=2018-09-25&rft_id=info%3Adoi%2F10.1117%2F1.jei.27.5.053013&rft_id=https%3A%2F%2Fapi.semanticscholar.org%2FCorpusID%3A53058660%23id-name%3DS2CID&rft.issn=1017-9909&rft_id=info%3Abibcode%2F2018JEI....27e3013B&rft.aulast=Brunnstr%C3%B6m&rft.aufirst=Kjell&rft.au=Barkowsky%2C+Marcus&rft_id=http%3A%2F%2Fmiun.diva-portal.org%2Fsmash%2Fget%2Fdiva2%3A1251082%2FFULLTEXT01&rfr_id=info%3Asid%2Fen.wikipedia.org%3ASubjective+video+quality" class="Z3988"></span></span> </li> <li id="cite_note-:3-5"><span class="mw-cite-backlink">^ <a href="#cite_ref-:3_5-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-:3_5-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFPinsonJanowskiPepionHuynh-Thu2012" class="citation journal cs1">Pinson, M. H.; Janowski, L.; Pepion, R.; Huynh-Thu, Q.; Schmidmer, C.; Corriveau, P.; Younkin, A.; Callet, P. Le; Barkowsky, M. (October 2012). <a rel="nofollow" class="external text" href="https://hal.archives-ouvertes.fr/hal-00725992/file/06286980.pdf">"The Influence of Subjects and Environment on Audiovisual Subjective Tests: An International Study"</a> <span class="cs1-format">(PDF)</span>. <i>IEEE Journal of Selected Topics in Signal Processing</i>. <b>6</b> (6): 640–651. <a href="/wiki/Bibcode_(identifier)" class="mw-redirect" title="Bibcode (identifier)">Bibcode</a>:<a rel="nofollow" class="external text" href="https://ui.adsabs.harvard.edu/abs/2012ISTSP...6..640P">2012ISTSP...6..640P</a>. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1109%2Fjstsp.2012.2215306">10.1109/jstsp.2012.2215306</a>. <a href="/wiki/ISSN_(identifier)" class="mw-redirect" title="ISSN (identifier)">ISSN</a> <a rel="nofollow" class="external text" href="https://search.worldcat.org/issn/1932-4553">1932-4553</a>. <a href="/wiki/S2CID_(identifier)" class="mw-redirect" title="S2CID (identifier)">S2CID</a> <a rel="nofollow" class="external text" href="https://api.semanticscholar.org/CorpusID:10667847">10667847</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=IEEE+Journal+of+Selected+Topics+in+Signal+Processing&rft.atitle=The+Influence+of+Subjects+and+Environment+on+Audiovisual+Subjective+Tests%3A+An+International+Study&rft.volume=6&rft.issue=6&rft.pages=640-651&rft.date=2012-10&rft_id=info%3Adoi%2F10.1109%2Fjstsp.2012.2215306&rft_id=https%3A%2F%2Fapi.semanticscholar.org%2FCorpusID%3A10667847%23id-name%3DS2CID&rft.issn=1932-4553&rft_id=info%3Abibcode%2F2012ISTSP...6..640P&rft.aulast=Pinson&rft.aufirst=M.+H.&rft.au=Janowski%2C+L.&rft.au=Pepion%2C+R.&rft.au=Huynh-Thu%2C+Q.&rft.au=Schmidmer%2C+C.&rft.au=Corriveau%2C+P.&rft.au=Younkin%2C+A.&rft.au=Callet%2C+P.+Le&rft.au=Barkowsky%2C+M.&rft_id=https%3A%2F%2Fhal.archives-ouvertes.fr%2Fhal-00725992%2Ffile%2F06286980.pdf&rfr_id=info%3Asid%2Fen.wikipedia.org%3ASubjective+video+quality" class="Z3988"></span></span> </li> <li id="cite_note-:2-6"><span class="mw-cite-backlink">^ <a href="#cite_ref-:2_6-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-:2_6-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text"><a rel="nofollow" class="external text" href="http://www.itu.int/rec/T-REC-P.913/en">ITU-T P.913: Methods for the subjective assessment of video quality, audio quality and audiovisual quality of Internet video and distribution quality television in any environment</a>, 2014.</span> </li> <li id="cite_note-:0-7"><span class="mw-cite-backlink">^ <a href="#cite_ref-:0_7-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-:0_7-1"><sup><i><b>b</b></i></sup></a> <a href="#cite_ref-:0_7-2"><sup><i><b>c</b></i></sup></a> <a href="#cite_ref-:0_7-3"><sup><i><b>d</b></i></sup></a> <a href="#cite_ref-:0_7-4"><sup><i><b>e</b></i></sup></a> <a href="#cite_ref-:0_7-5"><sup><i><b>f</b></i></sup></a></span> <span class="reference-text"><a rel="nofollow" class="external text" href="http://www.itu.int/rec/R-REC-BT.500/en">ITU-R BT.500: Methodology for the subjective assessment of the quality of television pictures</a>, 2012.</span> </li> <li id="cite_note-8"><span class="mw-cite-backlink"><b><a href="#cite_ref-8">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFHossfeld2014" class="citation journal cs1">Hossfeld, Tobias (2014-01-15). "Best Practices for QoE Crowdtesting: QoE Assessment With Crowdsourcing". <i>IEEE Transactions on Multimedia</i>. <b>16</b> (2): 541–558. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1109%2FTMM.2013.2291663">10.1109/TMM.2013.2291663</a>. <a href="/wiki/S2CID_(identifier)" class="mw-redirect" title="S2CID (identifier)">S2CID</a> <a rel="nofollow" class="external text" href="https://api.semanticscholar.org/CorpusID:16862362">16862362</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=IEEE+Transactions+on+Multimedia&rft.atitle=Best+Practices+for+QoE+Crowdtesting%3A+QoE+Assessment+With+Crowdsourcing&rft.volume=16&rft.issue=2&rft.pages=541-558&rft.date=2014-01-15&rft_id=info%3Adoi%2F10.1109%2FTMM.2013.2291663&rft_id=https%3A%2F%2Fapi.semanticscholar.org%2FCorpusID%3A16862362%23id-name%3DS2CID&rft.aulast=Hossfeld&rft.aufirst=Tobias&rfr_id=info%3Asid%2Fen.wikipedia.org%3ASubjective+video+quality" class="Z3988"></span></span> </li> <li id="cite_note-9"><span class="mw-cite-backlink"><b><a href="#cite_ref-9">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFHossfeldHirthRediMazza2014" class="citation journal cs1">Hossfeld, Tobias; Hirth, Matthias; Redi, Judith; Mazza, Filippo; Korshunov, Pavel; Naderi, Babak; Seufert, Michael; Gardlo, Bruno; Egger, Sebastian (October 2014). <a rel="nofollow" class="external text" href="https://hal.archives-ouvertes.fr/hal-01078761">"Best Practices and Recommendations for Crowdsourced QoE - Lessons learned from the Qualinet Task Force "Crowdsourcing"<span class="cs1-kern-right"></span>"</a>. hal-01078761.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.atitle=Best+Practices+and+Recommendations+for+Crowdsourced+QoE+-+Lessons+learned+from+the+Qualinet+Task+Force+%22Crowdsourcing%22&rft.date=2014-10&rft.aulast=Hossfeld&rft.aufirst=Tobias&rft.au=Hirth%2C+Matthias&rft.au=Redi%2C+Judith&rft.au=Mazza%2C+Filippo&rft.au=Korshunov%2C+Pavel&rft.au=Naderi%2C+Babak&rft.au=Seufert%2C+Michael&rft.au=Gardlo%2C+Bruno&rft.au=Egger%2C+Sebastian&rft_id=https%3A%2F%2Fhal.archives-ouvertes.fr%2Fhal-01078761&rfr_id=info%3Asid%2Fen.wikipedia.org%3ASubjective+video+quality" class="Z3988"></span> <span class="cs1-visible-error citation-comment"><code class="cs1-code">{{<a href="/wiki/Template:Cite_journal" title="Template:Cite journal">cite journal</a>}}</code>: </span><span class="cs1-visible-error citation-comment">Cite journal requires <code class="cs1-code">|journal=</code> (<a href="/wiki/Help:CS1_errors#missing_periodical" title="Help:CS1 errors">help</a>)</span></span> </li> <li id="cite_note-10"><span class="mw-cite-backlink"><b><a href="#cite_ref-10">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFJanowskiPinson2015" class="citation journal cs1">Janowski, Lucjan; Pinson, Margaret (2015). <a rel="nofollow" class="external text" href="https://doi.org/10.1109%2Ftmm.2015.2484963">"The Accuracy of Subjects in a Quality Experiment: A Theoretical Subject Model"</a>. <i>IEEE Transactions on Multimedia</i>. <b>17</b> (12): 2210–2224. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<span class="id-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://doi.org/10.1109%2Ftmm.2015.2484963">10.1109/tmm.2015.2484963</a></span>. <a href="/wiki/ISSN_(identifier)" class="mw-redirect" title="ISSN (identifier)">ISSN</a> <a rel="nofollow" class="external text" href="https://search.worldcat.org/issn/1520-9210">1520-9210</a>. <a href="/wiki/S2CID_(identifier)" class="mw-redirect" title="S2CID (identifier)">S2CID</a> <a rel="nofollow" class="external text" href="https://api.semanticscholar.org/CorpusID:22343847">22343847</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=IEEE+Transactions+on+Multimedia&rft.atitle=The+Accuracy+of+Subjects+in+a+Quality+Experiment%3A+A+Theoretical+Subject+Model&rft.volume=17&rft.issue=12&rft.pages=2210-2224&rft.date=2015&rft_id=https%3A%2F%2Fapi.semanticscholar.org%2FCorpusID%3A22343847%23id-name%3DS2CID&rft.issn=1520-9210&rft_id=info%3Adoi%2F10.1109%2Ftmm.2015.2484963&rft.aulast=Janowski&rft.aufirst=Lucjan&rft.au=Pinson%2C+Margaret&rft_id=https%3A%2F%2Fdoi.org%2F10.1109%252Ftmm.2015.2484963&rfr_id=info%3Asid%2Fen.wikipedia.org%3ASubjective+video+quality" class="Z3988"></span></span> </li> <li id="cite_note-11"><span class="mw-cite-backlink"><b><a href="#cite_ref-11">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFLiBampis2017" class="citation book cs1">Li, Zhi; Bampis, Christos G. (2017). "Recover Subjective Quality Scores from Noisy Measurements". <i>2017 Data Compression Conference (DCC)</i>. IEEE. pp. 52–61. <a href="/wiki/ArXiv_(identifier)" class="mw-redirect" title="ArXiv (identifier)">arXiv</a>:<span class="id-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://arxiv.org/abs/1611.01715">1611.01715</a></span>. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1109%2Fdcc.2017.26">10.1109/dcc.2017.26</a>. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/9781509067213" title="Special:BookSources/9781509067213"><bdi>9781509067213</bdi></a>. <a href="/wiki/S2CID_(identifier)" class="mw-redirect" title="S2CID (identifier)">S2CID</a> <a rel="nofollow" class="external text" href="https://api.semanticscholar.org/CorpusID:14251604">14251604</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=bookitem&rft.atitle=Recover+Subjective+Quality+Scores+from+Noisy+Measurements&rft.btitle=2017+Data+Compression+Conference+%28DCC%29&rft.pages=52-61&rft.pub=IEEE&rft.date=2017&rft_id=info%3Aarxiv%2F1611.01715&rft_id=https%3A%2F%2Fapi.semanticscholar.org%2FCorpusID%3A14251604%23id-name%3DS2CID&rft_id=info%3Adoi%2F10.1109%2Fdcc.2017.26&rft.isbn=9781509067213&rft.aulast=Li&rft.aufirst=Zhi&rft.au=Bampis%2C+Christos+G.&rfr_id=info%3Asid%2Fen.wikipedia.org%3ASubjective+video+quality" class="Z3988"></span></span> </li> <li id="cite_note-12"><span class="mw-cite-backlink"><b><a href="#cite_ref-12">^</a></b></span> <span class="reference-text">Pinson, Margaret and Wolf, Stephen. <a rel="nofollow" class="external text" href="http://www.its.bldrdoc.gov/publications/2577.aspx">"Comparing Subjective Video Quality Testing Methodologies"</a>. <i>SPIE Video Communications and Image Processing Conference</i>, Lugano, Switzerland, July 2003.</span> </li> </ol></div> <div class="mw-heading mw-heading2"><h2 id="External_links">External links</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Subjective_video_quality&action=edit&section=19" title="Edit section: External links"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <ul><li><a rel="nofollow" class="external text" href="https://vqeg.org/">Video Quality Experts Group</a></li></ul>    </div><noscript><img src="https://login.wikimedia.org/wiki/Special:CentralAutoLogin/start?type=1x1" alt="" width="1" height="1" style="border: none; position: absolute;"></noscript> <div class="printfooter" data-nosnippet="">Retrieved from "<a dir="ltr" href="https://en.wikipedia.org/w/index.php?title=Subjective_video_quality&oldid=1219212571">https://en.wikipedia.org/w/index.php?title=Subjective_video_quality&oldid=1219212571</a>"</div></div> <div id="catlinks" class="catlinks" data-mw="interface"><div id="mw-normal-catlinks" class="mw-normal-catlinks"><a href="/wiki/Help:Category" title="Help:Category">Categories</a>: <ul><li><a href="/wiki/Category:Film_and_video_technology" title="Category:Film and video technology">Film and video technology</a></li><li><a href="/wiki/Category:Digital_television" title="Category:Digital television">Digital television</a></li><li><a href="/wiki/Category:Video_codecs" title="Category:Video codecs">Video codecs</a></li></ul></div><div id="mw-hidden-catlinks" class="mw-hidden-catlinks mw-hidden-cats-hidden">Hidden categories: <ul><li><a href="/wiki/Category:CS1_errors:_missing_periodical" title="Category:CS1 errors: missing periodical">CS1 errors: missing periodical</a></li><li><a href="/wiki/Category:Articles_with_short_description" title="Category:Articles with short description">Articles with short description</a></li><li><a href="/wiki/Category:Short_description_is_different_from_Wikidata" title="Category:Short description is different from Wikidata">Short description is different from Wikidata</a></li></ul></div></div> </div> </main> </div> <div class="mw-footer-container"> <footer id="footer" class="mw-footer" > <ul id="footer-info"> <li id="footer-info-lastmod"> This page was last edited on 16 April 2024, at 11:42<span class="anonymous-show"> (UTC)</span>.</li> <li id="footer-info-copyright">Text is available under the <a href="/wiki/Wikipedia:Text_of_the_Creative_Commons_Attribution-ShareAlike_4.0_International_License" title="Wikipedia:Text of the Creative Commons Attribution-ShareAlike 4.0 International License">Creative Commons Attribution-ShareAlike 4.0 License</a>; additional terms may apply. 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