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Subjective Video Quality
Subjective video quality is video quality 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 video sequence. It is related to the field of Quality of Experience. Measuring subjective video quality is necessary because objective quality assessment algorithms such as PSNR have been shown to correlate poorly with subjective ratings. Subjective ratings may also be used as ground truth to develop new algorithms. Subjective video quality tests are psychophysical experiments 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. In subjective video quality tests, typically, SRCs ("Sources", i.e. original video sequences) are treated with various conditions (HRCs for "Hypothetical Reference Circuits") to generate PVSs ("Processed Video ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Video Quality
Video quality is a characteristic of a video passed through a video transmission or processing system that describes perceived video degradation (typically compared to the original video). Video processing systems may introduce some amount of distortion or artifacts in the video signal that negatively impact the user's perception of the system. For many stakeholders in video production and distribution, ensuring video quality is an important task. Video quality evaluation is performed to describe the quality of a set of video sequences under study. Video quality can be evaluated objectively (by mathematical models) or subjectively (by asking users for their rating). Also, the quality of a system can be determined offline (i.e., in a laboratory setting for developing new codecs or services) or in-service (to monitor and ensure a certain level of quality). From analog to digital video Since the world's first video sequence was recorded and transmitted, many video processing systems ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Normal Vision
Visual acuity (VA) commonly refers to the clarity of vision, but technically rates an animal's ability to recognize small details with precision. Visual acuity depends on optical and neural factors. Optical factors of the eye influence the sharpness of an image on its retina. Neural factors include the health and functioning of the retina, of the neural pathways to the brain, and of the interpretative faculty of the brain. The most commonly referred-to visual acuity is ''distance acuity'' or ''far acuity'' (e.g., "20/20 vision"), which describes someone's ability to recognize small details at a far distance. This ability is compromised in people with myopia, also known as short-sightedness or near-sightedness. Another visual acuity is '' near acuity'', which describes someone's ability to recognize small details at a near distance. This ability is compromised in people with hyperopia, also known as long-sightedness or far-sightedness. A common optical cause of low visual acuity ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Film And Video Technology
A film, also known as a movie or motion picture, is a work of visual art that simulates experiences and otherwise communicates ideas, stories, perceptions, emotions, or atmosphere through the use of moving images that are generally, since the 1930s, synchronized with sound and (less commonly) other sensory stimulations. Etymology and alternative terms The name "film" originally referred to the thin layer of photochemical emulsion on the celluloid strip that used to be the actual medium for recording and displaying motion pictures. Many other terms exist for an individual motion-picture, including "picture", "picture show", "moving picture", "photoplay", and "flick". The most common term in the United States is "movie", while in Europe, "film" is preferred. Archaic terms include "animated pictures" and "animated photography". "Flick" is, in general a slang term, first recorded in 1926. It originates in the verb flicker, owing to the flickering appearance of early films. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fade (audio Engineering)
In audio engineering, a fade is a gradual increase or decrease in the level of an audio signal. The term can also be used for film cinematography or theatre lighting in much the same way (see fade (filmmaking) and fade (lighting)). In sound recording and reproduction a song may be gradually reduced to silence at its end (fade-out), or may gradually increase from silence at the beginning (fade-in). Fading-out can serve as a recording solution for pieces of music that contain no obvious ending. Quick fade-ins and -outs can also be used to change the characteristics of a sound, such as to soften the attack in vocal plosives and percussion sounds. Professional turntablists and DJs in hip hop music use faders on a DJ mixer, notably the horizontal crossfader, in a rapid fashion while simultaneously manipulating two or more record players (or other sound sources) to create ''scratching'' and develop beats. Club DJs in house music and techno use DJ mixers, two or more sound s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quality Of Experience
Quality of experience (QoE) is a measure of the delight or annoyance of a customer's experiences with a service (e.g., web browsing, phone call, TV broadcast).Qualinet White Paper on Definitions of Quality of Experience (2012). European Network on Quality of Experience in Multimedia Systems and Services (COST Action IC 1003), Patrick Le Callet, Sebastian Möller and Andrew Perkis, eds., Lausanne, Switzerland, Version 1.2, March 2013 QoE focuses on the entire service experience; it is a holistic concept, similar to the field of user experience, but with its roots in telecommunication. QoE is an emerging multidisciplinary field based on social psychology, cognitive science, economics, and engineering science, focused on understanding overall human quality requirements. Definition and concepts In 2013, within the context of the COST Action ''QUALINET'', QoE has been defined as:The degree of delight or annoyance of the user of an application or service. It results from the fulfillm ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Crowdsourcing
Crowdsourcing involves a large group of dispersed participants contributing or producing goods or services—including ideas, votes, micro-tasks, and finances—for payment or as volunteers. Contemporary crowdsourcing often involves digital platforms to attract and divide work between participants to achieve a cumulative result. Crowdsourcing is not limited to online activity, however, and there are various historical examples of crowdsourcing. The word crowdsourcing is a portmanteau of "crowd" and "outsourcing". In contrast to outsourcing, crowdsourcing usually involves less specific and more public groups of participants. Advantages of using crowdsourcing include lowered costs, improved speed, improved quality, increased flexibility, and/or increased scalability of the work, as well as promoting diversity. Crowdsourcing methods include competitions, virtual labor markets, open online collaboration and data donation. Some forms of crowdsourcing, such as in "idea competiti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ishihara Test
The Ishihara test is a color vision test for detection of red–green color deficiencies. It was named after its designer, Shinobu Ishihara, a professor at the University of Tokyo, who first published his tests in 1917.S. Ishihara, Tests for color-blindness (Handaya, Tokyo, Hongo Harukicho, 1917). The test consists of a number of Ishihara plates, which are a type of pseudoisochromatic plate. Each plate depicts a solid circle of colored dots appearing randomized in color and size. Within the pattern are dots which form a number or shape clearly visible to those with normal color vision, and invisible, or difficult to see, to those with a red–green color vision deficiency. Other plates are intentionally designed to reveal numbers only to those with a red–green color vision deficiency, and be invisible to those with normal red–green color vision. The full test consists of 38 plates, but the existence of a severe deficiency is usually apparent after only a few plates. There ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Color Blindness
Color blindness, color vision deficiency (CVD) or color deficiency is the decreased ability to color vision, see color or differences in color. The severity of color blindness ranges from mostly unnoticeable to full absence of color perception. Color blindness is usually a Sex linkage, sex-linked Heredity, inherited problem or variation in the functionality of one or more of the three classes of cone cells in the retina, which mediate color vision. The most common form is caused by a genetic condition called congenital red–green color blindness (including protan and deutan types), which affects ''up to'' 1 in 12 males (8%) and 1 in 200 females (0.5%). The condition is more prevalent in males, because the opsin genes responsible are located on the X chromosome. Rarer genetic conditions causing color blindness include congenital blue–yellow color blindness (tritan type), blue cone monochromacy, and achromatopsia. Color blindness can also result from physical or chemical dam ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Snellen Chart
A Snellen chart is an eye chart that can be used to measure visual acuity. Snellen charts are named after the Dutch ophthalmologist Herman Snellen who developed the chart in 1862 as a measurement tool for the acuity formula developed by his professor Franciscus_Donders, Franciscus Cornelius Donders. Many ophthalmologists and vision scientists now use an improved chart known as the LogMAR chart. History Snellen developed charts using symbols based in a 5×5 unit grid. The experimental charts developed in 1861 used abstract symbols. Snellen's charts published in 1862 used alphanumeric capitals in the 5×5 grid. The original chart shows A, C, E, G, L, N, P, R, T, 5, V, Z, B, D, 4, F, H, K, O, S, 3, U, Y, A, C, E, G, L, 2. Description The normal Snellen chart is printed with eleven lines of block letters. The first line consists of one very large letter, which may be one of several letters, for example E, H, or N. Subsequent rows have increasing numbers of letters that decrease in s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Absolute Category Rating
Absolute Category Rating (ACR) is a test method used in quality Quality may refer to: Concepts *Quality (business), the ''non-inferiority'' or ''superiority'' of something *Quality (philosophy), an attribute or a property *Quality (physics), in response theory *Energy quality, used in various science discipli ... tests. The levels of the scale are, sorted by quality in decreasing order: * Excellent * Good * Fair * Poor * Bad In this method, a single test condition (generally an image or a video sequence) is presented to the viewers once only. They should then give a quality rating on an ACR scale. Test conditions should be presented in a random order per test person. The ACR scale is evaluated based on numbers that are assigned to the individual items, where ''Excellent'' equals to 5 and ''Bad'' equals to 1. The average numeric score over all experiment participants, for each test condition that was shown, is called the mean opinion score. It may also be used for telephony vo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Video
Video is an Electronics, electronic medium for the recording, copying, playback, broadcasting, and display of moving picture, moving image, visual Media (communication), media. Video was first developed for mechanical television systems, which were quickly replaced by cathode-ray tube (CRT) systems, which, in turn, were replaced by flat-panel displays of several types. Video systems vary in display resolution, Display aspect ratio, aspect ratio, refresh rate, color capabilities, and other qualities. Analog and digital variants exist and can be carried on a variety of media, including radio broadcasts, magnetic tape, optical discs, Video file format, computer files, and Streaming media, network streaming. Etymology The word ''video'' comes from the Latin verb ''video,'' meaning to see or ''videre''. And as a noun, "that which is displayed on a (television) screen," History Analog video Video developed from facsimile systems developed in the mid-19th century. Early mecha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
