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| Optimum [[High-definition television|HDTV]] viewing distance is the distance that provides the viewer with the optimum [[Immersion (virtual reality)|immersive]] visual HDTV experience. Although opinions vary on the exact screen size to distance relationship, formal research and recommendations suggest closer is preferred to farther{{failed verification|date=December 2010}}, to provide a more immersive experience.<ref name="future">{{Citation | last1 = Sugawara | first1 = M | last2 = Mitiani | first2 = K | last3 = Kanazawa | first3 = FM | last4 = Okano | first4 = F.| last5 = Nishida | first5 = Y | title = Future Prospects of HDTV –samsung trends Toward 1080p | year = 2005 | format = PDF | url = http://www.nhk.or.jp/digital/en/technical/pdf/02_1_1.pdf accessdate = 2009-04-20 }}</ref><ref name="hdtvmag">{{Citation | last = Fisher | first = R. | title = Waveform 03 Viewing Distance | date = 2005-06-08 | url = http://www.hdtvmagazine.com/forum/viewtopic.php?t=5282 | accessdate = 2009-04-18 }}</ref> How close? “As close as you can stand it”.{{Dubious|date=December 2010}}<ref name="hdhes">{{Citation | title = HDTV Size and Distance Calculations | url = http://www.hdhes.com/tv/hdtvviewdistance.aspx | accessdate = 2009-04-18 }}</ref><br />
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| [[File:Highdefinition.jpg|thumb|right|343px|Home Theater oriented room]]
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| == Background ==
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| HDTV is designed to provide the end user with an experience that is more realistic than the mediated experience of the [[television]] system it's designed to replace.<ref name="heart">{{Citation | last1 = Lombard | first1 = M. | last2 = Ditton | first2 = T. | title = At the Heart of It All: The concept of Presence | year = 1997 | url =http://jcmc.indiana.edu/vol3/issue2/lombard.html | accessdate = 2009-04-20 }}</ref> The “thrilling realism”<ref name="">{{Citation | title = 67" widescreen DLP HDTV HL67A510 – DLP TV – Samsung | url = http://www.samsung.com/us/consumer/detail/detail.do?group=televisions&type=televisions&subtype=dlptv&model_cd=HL67A510J1FXZA | accessdate = 2009-04-20 }}</ref> that HDTV attempts to offer, is courtesy of the increased [[Display resolution|resolution]] and the fact that the sets are typically larger than the analog sets they are superseding. This increase in the typical size of an HDTV set also increases the [[visual angle]] from which that [[Content (media and publishing)|content]] is viewed. Both of these factors, higher resolution and greater visual angle contribute to the feeling of [[Presence (telepresence)|presence]].<ref name="presence">{{Citation | last1 = Bracken | first1 = C.C. | last2 = Botta | first2 = R.A. | title = Presence and Television: Form verus Content | year = 2002 | url = http://www.temple.edu/ispr/prev_conferences/proceedings/2002/Final%20papers/Bracken%20and%20Botta.pdf | format = PDF | accessdate = 2009-04-20 }}</ref><ref name="vgame">{{Citation | last1 = Bracken | first1 = C.C. | last2 = Skalski | first2 = P. | title = Presence and video games: The impact of image quality and skill level | year = 2006 | format = PDF | url = http://www.temple.edu/ispr/prev_conferences/proceedings/2006/Bracken%20and%20Skalski.pdf | accessdate = 2009-04-20 }}</ref> Thus the correct viewing distance is critical to the enjoyment of HDTV in the manner intended. An early analysis was done by [[Bernard J. Lechner]], while working for RCA and helping define the HDTV standard. He studied the best viewing distances for various conditions and derived the so-called ''Lechner distance''.
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| === Presence ===
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| The concept of presence has been defined as the “sensation of reality”, of “being there” and as “an illusion of nonmediation”.<ref name="presence" /> The concept of presence originated and was studied with regard to [[Virtual reality|Virtual Reality (VR)]] and other [[Three-dimensional space|3D]] environments. It was later established that television viewers can also experience that feeling of presence.<ref name="presence" /> Presence can be influenced by a number of factors, including [[video camera]] techniques, audio fidelity, visual and aural dimensionality, and most relevant to this topic, [[image]] size (visual angle) and quality ([[angular resolution]]).<ref name="presenceTV">{{Citation | last1 = Lombard | first1 = M. | last2 = Reich | first2 = R.D. | last3 = Grabe | first3 = M.E. | last4 = Bracken | first4 = C.C. | last5 = Bitton | first5 = T. | title = Presence and Television – The Role of Screen Size | year = 2000 | format = PDF | url = http://www.wilcoxlab.yorku.ca/PresencePapers/Lombardetal2000.pdf | accessdate = 2009-04-15 }}</ref><ref name="Psychophysical">{{Citation | last1 = Hatada | first1 = T. | last2 = Sakata | first2 = H. | last3 = Kusaka | first3 = H. | title = Psychophysical Analysis of the "Sensation of Reality" Induced by a Visual Wide-Field Display | journal = SMPTE Journal | volume = 89 |date = August 1980| pages = 117–126 | format = PDF | url = http://vrsj.ime.cmc.osaka-u.ac.jp/ic-at/papers/91117.pdf | accessdate = 2009-04-20 }}</ref>
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| === Visual angle ===
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| The ideal optimum viewing distance is affected by the horizontal angle viewed by the camera capturing the image. One concept of an ideal optimal viewing distance places the viewer at a point where the horizontal angle subtended by the screen is the same as the horizontal angle captured by the camera. If this is the case, the angular relationships perceived by the viewer of objects viewed on the screen would be identical to the angular relationships viewed by the camera.
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| If the angle captured by the camera was always the same, an optimal viewing distance could be easily calculated. However the horizontal angle captured by the camera varies as the focal length of the camera lens changes. If the sensor has fixed dimensions, a shorter focal length (wide angle) lens captures a wider angle of view requiring the viewer to sit closer to the screen. Conversely a longer focal length (telephoto) lens captures a narrower angle of view demanding a more distant viewer position.
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| The more distant position demanded by a telephoto view would negate the reason for a telephoto image in the first place, to see more detail of a distant object, or perhaps minimize the distortion in facial images, for example. A wide angle view might require the viewer to sit too close to the screen, at a point where undesirable image artifacts would be visible.
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| One compromise assumes that the lens is "standard", a 50mm focal length in the case of a standard 35mm format. A "standard" lens preserves the same spacial relationships as perceived by a spectator at the camera location. For a "standard" lens image, the viewer should be placed a viewing distance equal to the diagonal length of the screen in the case of a projected standard 35mm image.
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| [[File:Angle of view.svg|thumb|right|190px|Horizontal, vertical and diagonal field of view.]]
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| It has been demonstrated that viewing content on a display that occupies a greater visual angle (also referred to as [[Field of view|field-of-view]]), increases the feeling of presence.<ref name="presenceTV" /> More importantly, the wider visual angle (to approximately a plateau point of 80 degrees) the greater the feeling of presence.<ref name="UHDTV">{{Citation | last1 = Sugawara | first1 = S. | last2 = Masaoka | first2 = K. | last3 = Emoto | first3 = M. | last4 = Matsuo | first4 = Y. | last5 = Nojiri | first5 = Y. | title = Research On Human Factors in Ultrahigh-Definition Television (UHDTV) to Determine its Specifications | journal = SMPTE Motion Imaging Journal |date = April 2008| pages = 23–29 | format = PDF | url = http://www.smpte.org/journal/?p=3101 |accessdate = 2009-02-42 }}</ref><ref name="Widen">{{Citation | last1 = Prothero | first1 = J.D. | last2 = Hoffman |first2 = H.G. | title = Widening the Field-of-View Increase the Sense of Presence in Immersive Virtual Environments | year = 1995 | url = http://www.hitl.washington.edu/publications/r-95-5/ | accessdate = 2009-04-20 }}</ref>
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| === Angular resolution ===
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| With printed [[graphics]], resolution refers the number of [[pixel]]s that occupy some fixed linear measurement.<ref name="photoshop">{{Citation | last1 = Fuller | first1 = Laurie Ulrich | last2 = Fuller | first2 = Robert C. | title = Photoshop CS3 Bible | publisher = Wiley Publishing, Inc. | year = 2004 | pages = 5, 75, 79 | isbn = 0-470-11541-6 }}</ref> With HDTV, resolution refers to image resolution and is not tied to a linear measurement. Instead, it is measured in terms of the physical display, (the total count of pixels available (or used) to compose the displayed image).<ref name="UHDTV" /> Generally, with printed graphics when the resolution of an image is increased, the image is cleaner, crisper and more detailed.<ref name="photoshop" /> The [[:wikt:caveat|caveat]] is, the image will not appear cleaner, crisper and more detailed, if the increase in resolution and the accompanying detail exceeds the visual system of the observer. If you exceed the viewer’s [[visual system]], there will be no perceived gain in image quality. For an HDTV image to gain a qualitative increase, what is important is that the resolution per [[Degree (angle)|degree of arc]] (or angular resolution) increases, not just the total pixel count of the display.<ref name="UHDTV" />
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| == Recommendations ==
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| To maximize the feeling of presence and thus provide a better viewing experience, the viewer would need to be situated at the theoretical spot where the HDTV occupies the widest view angle for that viewer{{Dubious|date=December 2010}}. It is also important that the resolution of the display per degree of arc remain at a high quality level.<ref name="future" /> Opinions regarding where the [[nirvana]] position lies are numerous and varied.
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| Recommendations on HDTV viewing distances fall into two general classes; a fixed distance based on HDTV display size, or a range of distances based on the display size. The most common recommendations from reasonably authoritative sources are presented below.
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| === Fixed distance ===
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| Fixed distance recommendations are the more common of the two types. For the most part, the majority of the fixed distance recommendations were issued before the end of 2007, when arguably HDTV displays were still in the [[Early adopter|early adoption]] phase.<ref name="nielson">{{Citation | title = Penetration of High Definition Television 23% | publisher = Nielsen | date = 2008-12-11 | url = http://blog.nielsen.com/nielsenwire/wp-content/uploads/2008/12/hdtv-december-2008-final1.pdf | accessdate = 2009-04-19 }}</ref><ref name="diffusion">{{Citation | last = Orr | first = G. | title = Diffusion of Innovation, by Everett Rogers (1995) | date = 2003-03-18 | url = http://www.stanford.edu/class/symbsys205/Diffusion%20of%20Innovations.htm | accessdate = 2009-04-19 }}</ref> The most frequently cited fixed distance recommendations are listed.
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| ==== Diagonal measurement × 2.5 (corresponding to 20-degree viewing angle) ====
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| One of the more popular recommendations on the proper HDTV viewing distance is multiply the [[diagonal]] measurement of the display screen by 2.5. This recommendation is cited by television manufacturers,<ref name="pioneer">{{Citation | title = Kuro Displays – Home Theater Design: Plasma Placement | url = http://www.pioneerelectronics.com/PUSA/Products/HomeEntertainment/PlasmaTVs+Monitors/Home+Theater+Design%3A+Plasma+Placement | accessdate = 2009-04-10 }}</ref> retailers,<ref name="bbfixed">{{Citation | last = Tinblock | first = E. | title = Guides & Resources – Calculate the optimal viewing distance for your TV | year = 2006 | url = http://www.bestbuy.ca/learnmore/buyersguide/en/viewing_distance.asp?logon=&langid=EN | accessdate = 2009-04-19 }}</ref> respected publications<ref name="electric1">{{Citation | last = Roth | first = B. | title = Displays: Angles, Distance Key to Home Theater Design | url = http://www.electronichouse.com/article/comfort_angle_seating_distance/D2 | accessdate = 2009-04-01 }}</ref><ref name="forbes">{{Citation | last = Brady | first = M.P. | title = Picture-Perfect HDTV | date = 2009-01-19 | url = http://www.forbes.com/2009/01/19/hdtv-improve-picture-tech-personal-cx_mpb_0119hdtv.html | accessdate = 2009-04-02 | work=Forbes}}</ref> and [[website]]s,<ref name="about">{{Citation | last = Silva | first = R. | title = About.com Top 10 Home Theater Mistakes and How to Avoid Then | url = http://hometheater.about.com/od/hometheaterbasics/tp/htmistakes.htm | accessdate = 2009-04-20 }}</ref> though the popular electronics review website CNET suggests that high-resolution content can be watched at a closer distance – 1.5 times the display screen's [[diagonal]] measurement (corresponding to 32 degree viewing angle).<ref name="cnet">{{Citation | last = Katzmeier | first = David | title = TV Buying Guide | url = http://reviews.cnet.com/tv-buying-guide/size-up-your-screen/ | accessdate = 2010-11-06 }}</ref>
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| ==== Diagonal measurement × 1.6 (corresponding to 30-degree viewing angle) ====
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| Viewing an HDTV from a position where the display occupies a 30 degree field of view is widely quoted as the [[Society of Motion Picture and Television Engineers|SMPTE]] (or SMPTE 30) recommendation (equivalent to about 1.6263 times the screen size in a 16:9 TV). This recommendation is very popular with the home theater enthusiast community,<ref name="soundV">{{Citation | last = Ranada | first = D. | title = Maxing Out Resolution (Optimize Your Seating Distance for Your Screen Size and Resolution) |date = March 2006| url = http://www.soundandvisionmag.com/hitech/1137/maxing-out-resolution.html | accessdate = 2009-04-20 }}</ref><ref name="electric2">{{Citation | last = Burger | first = D. | title = Howto: The Perfect TV for Your Room | date = 2008-04-08 | url = http://www.electronichouse.com/article/tv_size_vs_room_size/ | accessdate = 2009-04-20 }}</ref> appears in books on home theater design,<ref name="htd">{{Citation | last = Rushing | first = K. | title = Home Theater Design | publisher = Rockport Publishers | year = 2004 | page = 60 | isbn = 1-59253-017-6 }}</ref> and is also supported by a white paper produced by [[Fujitsu]].<ref name="fujitsu">{{Citation | title = Plasma Display Panel (PDP) vs. Liquid Crystal Display (LCD) Technology : An overview of Consumer Benefits for Home Theater Applications |date = September 2003| format = PDF | url = http://www.plasmavision.com/WhitePaperPlasmaVsLCD.pdf | accessdate = 2009-04-20 }}</ref> Although an article on research into setting the specification for the next evolution of HDTV, [[Ultra High Definition Television|Ultra HDTV]] (or UHDTV), does support the premise that HDTV was optimized for a view angle of 30 degrees,<ref name="UHDTV" /> there seems to be no direct recommendation from SMPTE on the issue.
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| ====Diagonal measurement × 1.2 (corresponding to 40-degree viewing angle)====
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| [[THX]] recommends that the “best seat-to-screen distance” is one where the view angle approximates 40 degrees,<ref name="thx1">{{Citation | title = THX Home Theater Display Setup | url = http://www.thx.com/home/setup/display.html | accessdate = 2009-04-01 }}</ref> (the actual angle is 40.04 degrees).<ref name="hdhes" /> Their recommendation was originally presented at the 2006 CES show, and was stated as being the theoretical maximum horizontal view angle, based on average human vision.<ref name="thx2">{{Citation | title = THX Home Theater 101 | year = 2006 | format = PDF | url = http://www.thx.com/library/pdf/THX_HT101-011906.pdf | accessdate = 2009-04-20 }}</ref> In the opinion of THX the location where the display is viewed at a 40 degree view angle provides the most “immersive cinematic experience”,<ref name="thx1" /> all other things considered. For [[consumer]] application of their recommendations, THX recommends dividing the diagonal screen measurement by .84 to calculate the optimum viewing distance, for a [[1080p]] resolution. This equates to multiplying the diagonal measurement with about 1.2.<ref name="thx1" />
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| === Optimum ranges ===
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| {{Tone|date=June 2011}}
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| Stating optimum viewing distance as a range rather than as fixed distance is on the rise; possibly because of changes in the profile of the typical HDTV purchaser. Early adopters of HDTV were typically [[videophile]]s,<ref name="ball">{{Citation | last = Fleischman | first = M. | title = Having a Ball with HDTV |date = September 2002| url = http://www.hometheatermag.com/bootcamp/132/index.html | accessdate = 2009-04-17 }}</ref> the technically adventurous<ref name="adventure">{{Citation | last = Taub | first = E.A. | title = Essay; High Definition TV: All or Nothing at All | date = 2001-02-15 | url = http://www.nytimes.com/2001/02/15/technology/essay-high-definition-tv-all-or-nothing-at-all.html?pagewanted=1 | accessdate = 2009-04-19 | work=The New York Times}}</ref> and the sports enthusiast<ref name="sports1">{{Citation | last = Taub | first = E.A. | title = Technology; HDTV’s Acceptance Picks Up Pace as Prices Drop and Networks Sign On | date = 2003-03-31 | url = http://www.nytimes.com/2003/03/31/business/technology-hdtv-s-acceptance-picks-up-pace-as-prices-drop-and-networks-sign-on.html?pagewanted=1 | accessdate = 2009-04-18 | work=The New York Times}}</ref> looking to have the ultimate viewing experience. Today, the typical HDTV consumer’s aims may be a little more modest; total immersion takes a back seat to room integration.<ref name="survival">{{Citation | last = Schiesel | first = S. | title = TV Maze: A Survival Guide | date = 2003-11-27 | url = http://www.nytimes.com/2003/11/27/technology/tv-maze-a-survival-guide.html | accessdate = 2009-04-19 | work=The New York Times}}</ref><ref name="videophile">{{Citation | last = Cripps | first = Dale | title = Waveform 05 Casual Viewer, Videophile or Critical Viewer? | date = 2004-10-15 | url = http://www.hdtvmagazine.com/forum/viewtopic.php?t=5345 | accessdate = 2009-04-20 }}</ref> Major retail chains like [[Best Buy]] that once stated their recommendation as a fixed distance,<ref name="bbfixed" /> are starting to provide range recommendations.<ref name="bestbuy">{{Citation | title = Choosing Your Screen Size | url = http://www.bestbuy.com/site/olspage.jsp?guideID=1151657987780&type=page&id=cat12077 | accessdate = 2009-04-10 }}</ref> Manufacturers have also started to provide range recommendations, updating their website with small applications that denote the optimum viewing distance as a range of distances.<ref name="toshiba">{{Citation | title = Toshiba Regza Room Planner | url = http://www.tacp.toshiba.com/regza/regzasite.aspx | accessdate = 2009-04-20 }}</ref><ref name="rca">{{Citation | title = RCA – Room Planner | url = http://tv.rca.com/en-US/home.html | accessdate = 2009-04-17 }}</ref><ref name="lg">{{Citation | title = LG – HDTV Viewing Distance Calculator | url = http://us.lge.com/GuidetoHDTV/why/size.html | accessdate = 2009-04-20 }}</ref> THX in March 2009, added range recommendations to their website.<ref name="thx1" /> The minimum end of the range tends to be the proponent’s fixed optimum distance recommendation.
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| ==== Manufacturers' recommendations ====
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| Range recommendations from manufacturers are the most modest of the groupings. For the minimum (or nearest) viewing distance, they recommend a view angle of approximately 31 degrees; and for the maximum, a view angle as low as 10 degrees.<ref name="toshiba" /><ref name="rca" /> A 10 degree view angle is approximately the angle that [[NTSC]] television was typically viewed from.<ref name="htmag">{{Citation | last = Morrison | first = G. | title = Viewing Distance vs. Resolution | work=Sound and Vision |url=http://www.soundandvision.com/content/viewing-distance-vs-resolution|date = September 2006| accessdate = 2009-04-12 }}</ref>
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| <br /> | |
| {| style="width:80%; margin:auto;"
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| |- style="vertical-align:top; text-align:center;"
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| | style="width:50%" |
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| {| class="wikitable" style="width:90%;" align:"center"
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| |+ RCA
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| |-
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| !Screen Size||Recommended Range
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| |- style="text-align:center;"
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| |22"||3'0" – 8'4" (0.9 – 2.5 m)
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| |- style="text-align:center;"
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| |26"||3'5" – 9'10" (1.0 – 3.0 m)
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| |- style="text-align:center;"
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| |32"||4'4" – 12'1" (1.3 – 3.7 m)
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| |- style="text-align:center;"
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| |40"||5'4" – 15'1" (1.6 – 4.6 m)
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| |- style="text-align:center;"
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| |42"||5'5" – 15'10" (1.7 – 4.8 m)
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| |- style="text-align:center;"
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| |52"||6'0" – 17'0" (1.8 – 5.2 m)
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| |}
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| | style="width:50%" |
| |
| {| class="wikitable" style="width:90%;" align:"center"
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| |+ TOSHIBA<ref>{{cite web|url=http://www.toshiba.com/us/recommended-tv-viewing-distance|title=Recommended TV Viewing Distance Chart|work=Toshiba Research Center|publisher=Toshiba|accessdate=November 14, 2013}}</ref>
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| |-
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| !Screen Size||Recommended Range
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| |- style="text-align:center;"
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| |40"||4.0’ - 6.3’
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| |- style="text-align:center;"
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| |42"||4.2’ - 6.7’
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| |- style="text-align:center;"
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| |46"||4.6’ - 7.3’
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| |- style="text-align:center;"
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| |47"||4.7’ - 7.4’
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| |- style="text-align:center;"
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| |50"||5.0’ - 7.9’
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| |- style="text-align:center;"
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| |55"||5.5’ - 8.7’
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| |- style="text-align:center;"
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| |65"||6.5’ - 10.3’
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| |}
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| |}
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| ==== Retail recommendations ====
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| The recommendations currently posted on the websites of retailers Best Buy and Crutchfield take more of a middle ground. Both retailers post a minimum viewing distance that accommodates a view angle of just a little over 32 degrees on average.<ref name="bestbuy" /><ref name="Kindig2009">{{Citation | last = Kindig | first = S. | title = TV and HDTV: Frequently Asked Questions | date = 2009-02-17 | url = http://www.crutchfield.com/learn/learningcenter/home/tv_faq.html#1 | accessdate = 2009-04-17 }}</ref> This viewing distance approximates the view angle needed to be able to see pixel level detail. The maximum viewing distance will provide a viewing angle of approximately 16 degrees with Best Buy’s recommendation and approximately 20 degrees with Crutchfield’s. The maximum viewing distance (minimum viewing angle) provided by Best Buy aligns with vision theory on the highest spatial frequencies perceivable by the [[Human visual system model|human visual system]].<ref name="limit">{{Citation | last = Deering | first = M.F. | title = The Limits of Human Vision | format = PDF | url = http://www.swift.ac.uk/about/files/vision.pdf | accessdate = 2009-04-20 }}</ref> Crutchfield’s maximum viewing distance aligns with the lower boundaries where viewers typically begin to find HDTV immersive.<ref name="UHDTV" />
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| <br /> | |
| {| style="width:80%; margin:auto;"
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| |- style="vertical-align:top; text-align:center;"
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| | style="width:50%" |
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| {| class="wikitable" style="width:90%;" align:"center"
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| |+ BEST BUY
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| |-
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| !Screen Size||Recommended Range
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| |- style="text-align:center;"
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| |26"||3.3' – 6.5' (1.0 m – 2.0 m)
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| |- style="text-align:center;"
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| |30"||3.8' – 7.6' (1.2 m – 2.3 m)
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| |- style="text-align:center;"
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| |34"||4.3' – 8.5' (1.3 m – 2.6 m)
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| |- style="text-align:center;"
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| |42"||5.3' – 10.5' (1.6 m – 3.2 m)
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| |- style="text-align:center;"
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| |46"||5.8' – 11.5' (1.8 m – 3.5 m)
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| |- style="text-align:center;"
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| |50"||6.3' – 12.5' (1.9 m – 3.8 m)
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| |- style="text-align:center;"
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| |55"||6.8' – 12.8' (2.1 m – 3.9 m)
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| |- style="text-align:center;"
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| |60"||7.5' – 15.0' (2.3 m – 4.6 m)
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| |- style="text-align:center;"
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| |65"||8.1' – 16.3' (2.5 m – 5.0 m)
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| |}
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| | style="width:50%" |
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| {| class="wikitable" style="width:90%;" align:"center"
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| |+ CRUTCHFIELD
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| |-
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| !Screen Size||Recommended Range
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| |- style="text-align:center;"
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| |26"||3.25' – 5.5' (1.0 m – 1.7 m)
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| |- style="text-align:center;"
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| |32"||4.0' – 6.66' (1.2 m – 2.0 m)
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| |- style="text-align:center;"
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| |37"||4.63' – 7.71' (1.4 m – 2.4 m)
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| |- style="text-align:center;"
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| |40"||5.0' – 8.33' (1.5 m – 2.5 m)
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| |- style="text-align:center;"
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| |42"||5.25' – 8.75' (1.6 m – 2.7 m)
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| |- style="text-align:center;"
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| |46"||5.75' – 9.5' (1.7 m – 2.9 m)
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| |- style="text-align:center;"
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| |50"||6.25' – 10.5' (1.9 m – 3.2 m)
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| |- style="text-align:center;"
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| |52"||6.5' – 10.8' (2.0 m – 3.3 m)
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| |- style="text-align:center;"
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| |55"||6.9' – 11.5' (2.1 m – 3.5 m)
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| |- style="text-align:center;"
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| |58"||7.25' – 12.0' (2.2 m – 3.7 m)
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| |- style="text-align:center;"
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| |65"||8.13' – 13.5' (2.5 m – 4.1 m)
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| |- style="text-align:center;"
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| |70"||8.75' – 14.75' (2.7 m – 4.5 m)
| |
| |}
| |
| |}
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| | |
| ==== THX ranges ====
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| While THX still contends that the optimum viewing distance is a position where the display occupies a 40 degree view angle for the viewer, they too provide a range recommendation. The minimum viewing distance is set to approximate a 40 degree view angle, and the maximum viewing distance is set to approximate 28 degrees.<ref name="thx1" />
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| {| class="wikitable" style="width:36%; margin:auto;"
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| |+ THX
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| |-
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| !Screen Size||Recommended Range
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| |- style="text-align:center;"
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| |35"||3.5' – 5.0' (1.0 – 1.5 m)
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| |- style="text-align:center;"
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| |40"||4.0' – 6.0' (1.2 – 1.8 m)
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| |- style="text-align:center;"
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| |50"||5' – 7.5' (1.5 – 2.2 m)
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| |- style="text-align:center;"
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| |60"||6.0' – 9.0' (1.8 – 2.7 m)
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| |}
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| ==Factors influencing the calculations==
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| Each recommendation serves the underlying goal of the organization that proposes it. Manufacturers will have an easier time selling their HDTVs if they support a position that does not require consumers to purchase as large a set as required by the THX recommendations. In the absence of economic influences, calculating the best screen size to distance ratio that will produce the utmost feeling of presence is not at all straightforward. There are a number of factors that can affect the calculation including the limitations of the human visual system,<ref name="UHDTV" /> the [[Technology|technological]] limitations of HDTV displays,<ref name="future" /> human [[Physiology|physiological]] considerations,<ref name="UHDTV" /> the content that will be viewed,<ref name="presenceTV" /> and the interpretation of [[empirical]] data from formal testing. There is also the fact that the screen image is on a flat plane and not curved. Perhaps the biggest of these are uncertainties surrounding the limits of the human visual system, and how those limitations apply to what we see and perceive. A further, more practical consideration, is one of room size, including the position of speakers, seating and other furniture in the room.
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| ===Human visual system limitation===
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| The human visual system has a fixed capacity to detect detail from a distance. Our understanding of limitations with regard to visual detail recognition and identification from a distance is primarily based on the work of [[Hermann Snellen|Dr. Hermann Snellen]]. Dr. Snellen developed the eye examination chart that bears his name [[Snellen chart|(Snellen Chart)]]. From his findings and the work of others over the last hundred years, one [[Minute of arc|arcminute]] is seen as the threshold beyond which critical detail cannot be identified,<ref name="webvision">{{Citation | last1 = Kolb | first1 = H. | last2 = Fernandez |first2 = E. | last3 = Nelson | first3 = R. | title = Webvision – The organization of the Retina and Visual System | url = http://webvision.med.utah.edu/KallSpatial.html#introduction | accessdate = 2009-04-18 }}</ref> by a person with normal vision.<ref name="adaptation">{{Citation | last1 = Ferwerda | first1 = J.A. | last2 = Pattanaik | first2 = S.N. | last3 = Shirley | first3 = P. | last4 = Greenberg | first4 = D.P. | title = A Model of Visual Adaptation for Realistic Image Synthesis | date =1995-06-20 | format = PDF | url = http://www.cis.rit.edu/jaf/publications/sig96_paper.pdf | accessdate = 2009-04-20 }}</ref><ref name="aoa">{{Citation | title = Visual Acuity: What is 20/20 Vision? | url = http://www.aoa.org/x4695.xml | accessdate = 2009-04-15 }}</ref><ref name="mdsupport">{{Citation | last = Watt | first = W.S. | title = How Visual Acuity is Measured | url = http://www.mdsupport.org/library/acuity.html | accessdate = 2009-04-20 }}</ref> An arcminute is an angular measurement, which is equal to 1/60 of one degree of a circle. Normal vision is referenced as 20/20 or 6/6 vision in North America and Europe respectively.<ref name="mdsupport" /><ref name="standard">{{Citation | last = Evans | first = J.M. | title = Standards for Visual Acuity | date = 2006-06-16 | format = PDF | url = http://www.isd.mel.nist.gov/US&R_Robot_Standards/Visual_Acuity_Standards_1.pdf | accessdate =2009-04-17 }}</ref> The [[visual acuity]] threshold has been identified as a constraint factor in the recommendations on the optimum viewing distance for HDTV,<ref name="htmag" /> and also in formal research that comment on the subject of television and angular resolution.<ref name="future" /><ref name="bbc">{{Citation | last1 = Drewery | first1 = J.O. | last2 = Salmon | first2 = R.A. | title = Tests of Visual acuity to determine the resolution required of a television transmission system – BBC |date = September 2004| format = PDF | url=http://www.bbc.co.uk/rd/pubs/whp/whp092.shtml | accessdate = 2009-04-10 }}</ref><ref name="super">{{Citation | last = Sugawara | first = M. | title = Super Hi-Vision – research on a future ultra-HDTV system | year = 2008 | format = PDF | url = http://www.ebu.ch/fr/technical/trev/trev_2008-Q2_nhk-ultra-hd.pdf | accessdate = 2009-04-18 }}</ref><ref name="eye">{{Citation | last1 =Forrester | first1 = J.V. | last2 = Dick | first2 = A.D. | last3 = McMenamin | last4 = Lee | first4 = W.R. | title = The Eye | publisher = Elsevier Health Sciences | year = 2002 | edition = 2nd | page = 229 | first3 = P.G. | isbn =0-7020-1790-6 }}</ref> Assuming display is flat, with 1 arcminute as the constraint for seeing critical detail, in order not to miss any detail a viewer would need to be situated at a position where their view angle to a 1080p HDTV is approximately 31.2 degrees or greater (32 degrees for spherical display), for 2160p HDTV approximately 58.37 degrees or greater (64 degrees for spherical display) and for 4320p HDTV approximately 96.33 degrees or greater (128 degrees for spherical display).<ref name="future" /><ref name="hdhes" /> However, there is not always agreement that the Snellenian limit should be the constraining factor.
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| To calculate the viewing distance, based on display size and content resolution, the following formula may be used:
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| {|
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| |- valign="top"
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| | style="width:50%;"|<math>\textrm{VD}=\frac{\textrm{DS}}{\sqrt{\left(\frac{\textrm{NHR}}{\textrm{NVR}}\right)^2+1} \cdot \textrm{CVR} \cdot \tan{\frac{1}{60}}}</math>
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| <small>
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| :Where:
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| ::VD: Viewing distance
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| ::DS: Display's diagonal size
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| ::NHR: Display's native horizontal resolution (in pixels)
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| ::NVR: Display's native vertical resolution (in pixels)
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| ::CVR: Vertical resolution of the video being displayed (in pixels)
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| :Note: Make sure the angle mode is set to degrees when calculating the tangent. If using a spreadsheet such as [[Microsoft Excel|Excel]], you must multiply the angle by PI()/180. If DS is given in inches, VD will be in inches. If VD in meters is desired, multiply VD by 2.54 and divide by 100.</small>
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| |Example for [[DVD video]] on a 32-inch 1080p HDTV:
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| <math>\textrm{VD}=\frac{\textrm{32}}{\sqrt{\left(\frac{\textrm{1920}}{\textrm{1080}}\right)^2+1} \cdot \textrm{480} \cdot \tan{\frac{1}{60}}}=112.36</math> (inches)
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| Example for high-def video on a 32-inch 1080p HDTV:
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| <math>\textrm{VD}=\frac{\textrm{32}}{\sqrt{\left(\frac{\textrm{1920}}{\textrm{1080}}\right)^2+1} \cdot \textrm{1080} \cdot \tan{\frac{1}{60}}}=49.94</math> (inches)
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| |}
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| Sitting beyond these distances will result in a loss of detail.
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| A 1998 [[Sun Microsystems]] paper on the limits of human vision and video display systems uses a different constraint value of approximately ½ an arc minute (or 30 arc seconds), when estimating the saturation point for the human visual system.<ref name="limit" /> With 30 arc seconds as the constraint, the view angle necessary to see all the detail provided by an HDTV with a 1080p resolution drops to approximately 16.1 degrees. Furthermore, several [[Academia|academic]] articles have challenged the notion that 1 arcminute of resolution is the typical resolving power of the human eye, suggesting that on average, we can resolve detail smaller than that.<ref name="standard" /><ref name="physical">{{Citation | last = Geisler | first = W.S. | title = Physical limits of acuity and hyperacuity | year = 1984 | format = PDF | url = http://www.cps.utexas.edu/Research/Geisler/PDF%20files/JOSA-A_1984_Physical_limits.pdf | accessdate =2009-04-20 }}</ref> Also, there is the issue of [[vernier acuity]], which is the eye’s ability to detect an offset between 2 lines and [[Stereopsis|stereoacuity]], which is the ability to discriminate depth by the use of both eyes. Vernier acuity and stereoacuity are cited as being detected with only a 2–4 arc second degree of separation.<ref name="synthesis">{{Citation | last = McNamara | first = A. | title = Visual Perception in Realistic Image Synthesis | year = 2001 | format = PDF| url = https://www.cs.tcd.ie/courses/baict/bass/4ict10/Ann/VPinRIS.pdf | accessdate = 2009-04-06 }}</ref> Ultimately all of the various types of acuity play a part in how we see things and more importantly, how we perceive what we are witnessing. The complexities of the human visual system and the relationship between different types of acuity are not yet fully understood.<ref name="synthesis" /> Thus, depending on which human visual system constraints are applied, viewing angles calculations will vary to some degree, especially when technological constraints are factored in.
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| ===Technology limitations===
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| [[File:Progressive scan hdtv.svg|thumb|right|250px|Magnification of the pixel grid]][[File:Pixel-example.png|thumb|right|250px|This example shows an image with a portion greatly enlarged, in which the individual pixels are rendered as little squares that can easily be seen.]]
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| Blindly applying the principles that give rise to an increased sense of presence can put the viewer too close to the display. Viewing the display from too close can have an adverse effect, due to the limitations of technology. Get too close to an [[Liquid crystal display|LCD]] or [[Plasma display|plasma]] HDTV display when it is turned off and the construction of the pixel grid is very evident. Unfortunately, turning the display on doesn’t completely mask the pixel grid. If you are still too close to the set, it will look like you’re viewing the display through a screen door.<ref name="super" /><ref name="nytimes">{{Citation | last = Pugue | first = D. | title = How Far From HDTV? | date = 2004-12-16 | url = http://www.nytimes.com/2004/12/16/technology/circuits/16POGUE-EMAIL.html | accessdate = 2009-04-16 | work=The New York Times}}</ref> Even if you use a different HDTV display technology such as front or rear projection [[Digital Light Processing|DLP]], [[Liquid crystal on silicon|LCoS]], or [[Laser video display|laser TV]], the manner in which HDTV display images are rendered still constrains how close a viewer can be to an HDTV before they experience adverse effects. HDTV displays have a fixed maximum resolution; the images produced by the display consist of rows and columns of pixels, the same way that a computer [[bitmap]] (also known as [[Raster graphics|raster]]) graphic is produced. Having a fixed number of pixels is where the problem lies; the image is a [[mosaic]] of colored 4 sided pixels. Viewed from far enough away, the pixels blend together to create a complete and smooth image.<ref name="photoshop" /> As you get closer to the HDTV image, you will eventually reach a point where image pixelation happens and the blocky appearance of individual pixels becomes visible.<ref name="future" /> When the blocky nature of individual pixels starts to become evident, the overall image begins to lose its smoothness. Once this happens, the perceived quality of the displayed images drops, and the advantages of moving closer produces unfavourable effects.
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| Even if the unknowns about human vision are eliminated from the equation, calculating the point where pixels will begin to reveal their blocky nature is still not straight forward. The pixel geometry can vary to some degree, both in shape and in the spaces between each pixel (referred to as the inter-pixel spacing or inter-pixel gap).<ref name="htmag" /> This variability, which differs both by technology and individual models makes it dicey to establish the exact common point where pixel geometry will become the limiting factor.
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| ===Human physiological considerations===
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| Research conducted on presence with HDTV and other higher resolution formats that use a wide field display, has revealed that sometimes the feeling of presence can be too real, producing physiological effect that some viewers may find undesirable. Subjects have reported experiencing an increase in symptoms that are common to [[motion sickness]] when viewing strong visual stimuli on large screens.<ref name="UHDTV" /> A study conducted using virtual reality simulation as part of the experiment, found that subjects with lower visual acuity experienced significantly more of the symptoms associated with motion sickness. Furthermore, the study also found that the symptoms of motion sickness increased when subjects observed the visual stimuli without the aid of their glass or contact lenses.<ref name="motion">{{Citation | last = Webb | first = N.A. | title = Visual Acuity, Eye Movements, the Illusion of Motion and Motion Sickness with Optokinetic stimuli | year = 2004 | url = http://www.motion-sickness.co.uk/ | accessdate = 2009-04-15 }}</ref> Consequently, optimum viewing distance recommendations based solely on human visual system and technological limitations may not always produce the best viewing experience. Viewers with lower visual acuity, who prefer to watch HDTV without their corrective lenses may want to sit closer to see critical details and run the risk of undesirable side effects.
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| ===End-user content selection===
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| Although studies show the feeling of presence and image size are directly correlated, calculating the size to viewing distance relationship may not be a necessary exercise for all consumers. A 1997 study, which [[Hypothesis|hypothesized]] that increases in screen size would give rise to increased feelings of presence, found that the content was more important than the screen size. The findings were that for [[Television advertisement|commercials]], action-adventure and [[Reality television|reality programming]] an increase in the feeling of presence did correlate with increased size. The researcher attributed these findings to the fact that the aforementioned content contained scenes that were shot with a point of view camera, scenes with sudden movements and shorter shots. Conversely, for programming consisting of [[talk show]]s and [[Dramatic programming|drama programs]] changing the screen size had no effect on the feeling of presence.<ref name="enduser">{{Citation | last1 = Lombard | first1 = M. | last2 = Ditton | first2 = T.B. | last3 = Grabe | first3 = M.E. | last4 = Reich | first4 = R.D. | title = The Role of Screen size in Viewer Responses to Television Fare | year = 1997 | format = PDF | url = http://www.wilcoxlab.yorku.ca/PresencePapers/Lombardetal1997.pdf | accessdate = 2009-04-12 }}</ref>
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| == See also ==
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| *[[Contrast (vision)|Contrast sensitivity]]
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| *[[Angle of view|View Angle]]
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| *[[Large-screen television technology]]
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| *[[High-definition television|HDTV]]
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| *[[Home cinema|Home Theater]]
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| *[[Sweet spot (acoustics)]]
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| == References ==
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| {{Reflist|35em}}
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| {{Display technology}}
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| {{DEFAULTSORT:Optimum Hdtv Viewing Distance}}
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| [[Category:High-definition television]]
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