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href="https://ar.wikipedia.org/wiki/%D8%B3%D8%B7%D9%88%D8%B9" title="سطوع – Arabic" lang="ar" hreflang="ar" data-title="سطوع" data-language-autonym="العربية" data-language-local-name="Arabic" class="interlanguage-link-target"><span>العربية</span></a></li><li class="interlanguage-link interwiki-zh-min-nan mw-list-item"><a href="https://zh-min-nan.wikipedia.org/wiki/B%C3%AAng-t%C5%8D%CD%98" title="Bêng-tō͘ – Minnan" lang="nan" hreflang="nan" data-title="Bêng-tō͘" data-language-autonym="閩南語 / Bân-lâm-gú" data-language-local-name="Minnan" class="interlanguage-link-target"><span>閩南語 / Bân-lâm-gú</span></a></li><li class="interlanguage-link interwiki-bg mw-list-item"><a href="https://bg.wikipedia.org/wiki/%D0%AF%D1%80%D0%BA%D0%BE%D1%81%D1%82" title="Яркост – Bulgarian" lang="bg" hreflang="bg" data-title="Яркост" data-language-autonym="Български" data-language-local-name="Bulgarian" class="interlanguage-link-target"><span>Български</span></a></li><li class="interlanguage-link interwiki-ca mw-list-item"><a href="https://ca.wikipedia.org/wiki/Brillantor" title="Brillantor – Catalan" lang="ca" hreflang="ca" data-title="Brillantor" data-language-autonym="Català" data-language-local-name="Catalan" class="interlanguage-link-target"><span>Català</span></a></li><li class="interlanguage-link interwiki-de mw-list-item"><a href="https://de.wikipedia.org/wiki/Helligkeit" title="Helligkeit – German" lang="de" hreflang="de" data-title="Helligkeit" data-language-autonym="Deutsch" data-language-local-name="German" class="interlanguage-link-target"><span>Deutsch</span></a></li><li class="interlanguage-link interwiki-el mw-list-item"><a href="https://el.wikipedia.org/wiki/%CE%A6%CF%89%CF%84%CE%B5%CE%B9%CE%BD%CF%8C%CF%84%CE%B7%CF%84%CE%B1" title="Φωτεινότητα – Greek" lang="el" hreflang="el" data-title="Φωτεινότητα" data-language-autonym="Ελληνικά" data-language-local-name="Greek" class="interlanguage-link-target"><span>Ελληνικά</span></a></li><li class="interlanguage-link interwiki-es badge-Q70893996 mw-list-item" title=""><a href="https://es.wikipedia.org/wiki/Luminosidad_superficial" title="Luminosidad superficial – Spanish" lang="es" hreflang="es" data-title="Luminosidad superficial" data-language-autonym="Español" data-language-local-name="Spanish" class="interlanguage-link-target"><span>Español</span></a></li><li class="interlanguage-link interwiki-eu mw-list-item"><a href="https://eu.wikipedia.org/wiki/Distira" title="Distira – Basque" lang="eu" hreflang="eu" data-title="Distira" data-language-autonym="Euskara" data-language-local-name="Basque" class="interlanguage-link-target"><span>Euskara</span></a></li><li class="interlanguage-link interwiki-fa mw-list-item"><a href="https://fa.wikipedia.org/wiki/%D8%B1%D9%88%D8%B4%D9%86%D8%A7%DB%8C%DB%8C" title="روشنایی – Persian" lang="fa" hreflang="fa" data-title="روشنایی" data-language-autonym="فارسی" data-language-local-name="Persian" class="interlanguage-link-target"><span>فارسی</span></a></li><li class="interlanguage-link interwiki-ko mw-list-item"><a href="https://ko.wikipedia.org/wiki/%EB%AA%85%EB%8F%84" title="명도 – Korean" lang="ko" hreflang="ko" data-title="명도" data-language-autonym="한국어" data-language-local-name="Korean" class="interlanguage-link-target"><span>한국어</span></a></li><li class="interlanguage-link interwiki-hi mw-list-item"><a href="https://hi.wikipedia.org/wiki/%E0%A4%9A%E0%A4%AE%E0%A4%95" title="चमक – Hindi" lang="hi" hreflang="hi" data-title="चमक" data-language-autonym="हिन्दी" data-language-local-name="Hindi" class="interlanguage-link-target"><span>हिन्दी</span></a></li><li class="interlanguage-link interwiki-id mw-list-item"><a href="https://id.wikipedia.org/wiki/Kecerahan" title="Kecerahan – Indonesian" lang="id" hreflang="id" data-title="Kecerahan" data-language-autonym="Bahasa Indonesia" data-language-local-name="Indonesian" class="interlanguage-link-target"><span>Bahasa Indonesia</span></a></li><li class="interlanguage-link interwiki-it mw-list-item"><a href="https://it.wikipedia.org/wiki/Luminosit%C3%A0_(percezione)" title="Luminosità (percezione) – Italian" lang="it" hreflang="it" data-title="Luminosità (percezione)" data-language-autonym="Italiano" data-language-local-name="Italian" class="interlanguage-link-target"><span>Italiano</span></a></li><li class="interlanguage-link interwiki-hu mw-list-item"><a href="https://hu.wikipedia.org/wiki/Vil%C3%A1goss%C3%A1g" title="Világosság – Hungarian" lang="hu" hreflang="hu" data-title="Világosság" data-language-autonym="Magyar" data-language-local-name="Hungarian" class="interlanguage-link-target"><span>Magyar</span></a></li><li class="interlanguage-link interwiki-mk mw-list-item"><a href="https://mk.wikipedia.org/wiki/%D0%A1%D0%B2%D0%B5%D1%82%D0%BB%D0%BE%D1%81%D1%82" title="Светлост – Macedonian" lang="mk" hreflang="mk" data-title="Светлост" data-language-autonym="Македонски" data-language-local-name="Macedonian" class="interlanguage-link-target"><span>Македонски</span></a></li><li class="interlanguage-link interwiki-ms mw-list-item"><a href="https://ms.wikipedia.org/wiki/Kecerahan" title="Kecerahan – Malay" lang="ms" hreflang="ms" data-title="Kecerahan" data-language-autonym="Bahasa Melayu" data-language-local-name="Malay" class="interlanguage-link-target"><span>Bahasa Melayu</span></a></li><li class="interlanguage-link interwiki-ja mw-list-item"><a href="https://ja.wikipedia.org/wiki/%E3%83%96%E3%83%A9%E3%82%A4%E3%83%88%E3%83%8D%E3%82%B9" title="ブライトネス – Japanese" lang="ja" hreflang="ja" data-title="ブライトネス" data-language-autonym="日本語" data-language-local-name="Japanese" class="interlanguage-link-target"><span>日本語</span></a></li><li class="interlanguage-link interwiki-ps mw-list-item"><a href="https://ps.wikipedia.org/wiki/%D8%B1%D9%88%DA%9A%D9%86%D8%A7%D9%8A%D9%8A" title="روښنايي – Pashto" lang="ps" hreflang="ps" data-title="روښنايي" data-language-autonym="پښتو" data-language-local-name="Pashto" class="interlanguage-link-target"><span>پښتو</span></a></li><li class="interlanguage-link interwiki-pl mw-list-item"><a href="https://pl.wikipedia.org/wiki/Jasno%C5%9B%C4%87_koloru" title="Jasność koloru – Polish" lang="pl" hreflang="pl" data-title="Jasność koloru" data-language-autonym="Polski" data-language-local-name="Polish" class="interlanguage-link-target"><span>Polski</span></a></li><li class="interlanguage-link interwiki-pt mw-list-item"><a href="https://pt.wikipedia.org/wiki/Brilh%C3%A2ncia" title="Brilhância – Portuguese" lang="pt" hreflang="pt" data-title="Brilhância" data-language-autonym="Português" data-language-local-name="Portuguese" class="interlanguage-link-target"><span>Português</span></a></li><li class="interlanguage-link interwiki-ru mw-list-item"><a href="https://ru.wikipedia.org/wiki/%D0%AF%D1%80%D0%BA%D0%BE%D1%81%D1%82%D1%8C_(%D1%86%D0%B2%D0%B5%D1%82%D0%BE%D0%B2%D0%BE%D1%81%D0%BF%D1%80%D0%B8%D1%8F%D1%82%D0%B8%D0%B5)" title="Яркость (цветовосприятие) – Russian" lang="ru" hreflang="ru" data-title="Яркость (цветовосприятие)" data-language-autonym="Русский" data-language-local-name="Russian" class="interlanguage-link-target"><span>Русский</span></a></li><li class="interlanguage-link interwiki-sr mw-list-item"><a href="https://sr.wikipedia.org/wiki/%D0%A1%D1%98%D0%B0%D1%98%D0%BD%D0%BE%D1%81%D1%82" title="Сјајност – Serbian" lang="sr" hreflang="sr" data-title="Сјајност" data-language-autonym="Српски / srpski" data-language-local-name="Serbian" class="interlanguage-link-target"><span>Српски / srpski</span></a></li><li class="interlanguage-link interwiki-ta mw-list-item"><a href="https://ta.wikipedia.org/wiki/%E0%AE%92%E0%AE%B3%E0%AE%BF%E0%AE%B0%E0%AF%8D%E0%AE%AE%E0%AF%88" title="ஒளிர்மை – Tamil" lang="ta" hreflang="ta" data-title="ஒளிர்மை" data-language-autonym="தமிழ்" data-language-local-name="Tamil" class="interlanguage-link-target"><span>தமிழ்</span></a></li><li class="interlanguage-link interwiki-th mw-list-item"><a href="https://th.wikipedia.org/wiki/%E0%B8%84%E0%B8%A7%E0%B8%B2%E0%B8%A1%E0%B8%AA%E0%B8%A7%E0%B9%88%E0%B8%B2%E0%B8%87" title="ความสว่าง – Thai" lang="th" hreflang="th" data-title="ความสว่าง" data-language-autonym="ไทย" data-language-local-name="Thai" class="interlanguage-link-target"><span>ไทย</span></a></li><li class="interlanguage-link interwiki-tr mw-list-item"><a href="https://tr.wikipedia.org/wiki/Parlakl%C4%B1k" title="Parlaklık – Turkish" lang="tr" hreflang="tr" data-title="Parlaklık" data-language-autonym="Türkçe" data-language-local-name="Turkish" class="interlanguage-link-target"><span>Türkçe</span></a></li><li class="interlanguage-link interwiki-uk mw-list-item"><a href="https://uk.wikipedia.org/wiki/%D0%AF%D1%81%D0%BA%D1%80%D0%B0%D0%B2%D1%96%D1%81%D1%82%D1%8C_(%D0%BA%D0%BE%D0%BB%D1%8C%D0%BE%D1%80%D0%BE%D1%81%D0%BF%D1%80%D0%B8%D0%B9%D0%BD%D1%8F%D1%82%D1%82%D1%8F)" title="Яскравість (кольоросприйняття) – Ukrainian" lang="uk" hreflang="uk" data-title="Яскравість (кольоросприйняття)" data-language-autonym="Українська" data-language-local-name="Ukrainian" class="interlanguage-link-target"><span>Українська</span></a></li><li class="interlanguage-link interwiki-vi mw-list-item"><a href="https://vi.wikipedia.org/wiki/%C4%90%E1%BB%99_tr%E1%BA%AFng" title="Độ trắng – Vietnamese" lang="vi" hreflang="vi" data-title="Độ trắng" data-language-autonym="Tiếng Việt" data-language-local-name="Vietnamese" class="interlanguage-link-target"><span>Tiếng Việt</span></a></li><li class="interlanguage-link interwiki-wuu mw-list-item"><a href="https://wuu.wikipedia.org/wiki/%E6%98%8E%E5%BA%A6" title="明度 – Wu" lang="wuu" hreflang="wuu" data-title="明度" data-language-autonym="吴语" data-language-local-name="Wu" class="interlanguage-link-target"><span>吴语</span></a></li><li class="interlanguage-link interwiki-zh-yue mw-list-item"><a href="https://zh-yue.wikipedia.org/wiki/%E5%85%89%E5%BA%A6" title="光度 – Cantonese" lang="yue" hreflang="yue" data-title="光度" data-language-autonym="粵語" data-language-local-name="Cantonese" class="interlanguage-link-target"><span>粵語</span></a></li><li class="interlanguage-link interwiki-zh mw-list-item"><a href="https://zh.wikipedia.org/wiki/%E8%A7%86%E4%BA%AE%E5%BA%A6" title="视亮度 – Chinese" lang="zh" hreflang="zh" data-title="视亮度" data-language-autonym="中文" data-language-local-name="Chinese" class="interlanguage-link-target"><span>中文</span></a></li> </ul> <div class="after-portlet after-portlet-lang"><span class="wb-langlinks-edit wb-langlinks-link"><a href="https://www.wikidata.org/wiki/Special:EntityPage/Q221656#sitelinks-wikipedia" title="Edit interlanguage links" class="wbc-editpage">Edit links</a></span></div> </div> </div> </div> </header> <div class="vector-page-toolbar"> <div class="vector-page-toolbar-container"> <div id="left-navigation"> <nav aria-label="Namespaces"> <div id="p-associated-pages" class="vector-menu vector-menu-tabs mw-portlet mw-portlet-associated-pages" > <div 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<div class="vector-body-before-content"> <div class="mw-indicators"> </div> <div id="siteSub" class="noprint">From Wikipedia, the free encyclopedia</div> </div> <div id="contentSub"><div id="mw-content-subtitle"></div></div> <div id="mw-content-text" class="mw-body-content"><div class="mw-content-ltr mw-parser-output" lang="en" dir="ltr"><div class="shortdescription nomobile noexcerpt noprint searchaux" style="display:none">Perception of light level</div> <style data-mw-deduplicate="TemplateStyles:r1236090951">.mw-parser-output .hatnote{font-style:italic}.mw-parser-output div.hatnote{padding-left:1.6em;margin-bottom:0.5em}.mw-parser-output .hatnote i{font-style:normal}.mw-parser-output .hatnote+link+.hatnote{margin-top:-0.5em}@media print{body.ns-0 .mw-parser-output .hatnote{display:none!important}}</style><div role="note" class="hatnote navigation-not-searchable">For other uses, see <a href="/wiki/Brightness_(disambiguation)" class="mw-disambig" title="Brightness (disambiguation)">Brightness (disambiguation)</a>.</div> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:LightningVolt_Deep_Blue_Sea.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/a/a5/LightningVolt_Deep_Blue_Sea.jpg/220px-LightningVolt_Deep_Blue_Sea.jpg" decoding="async" width="220" height="275" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/a/a5/LightningVolt_Deep_Blue_Sea.jpg/330px-LightningVolt_Deep_Blue_Sea.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/a/a5/LightningVolt_Deep_Blue_Sea.jpg 2x" data-file-width="384" data-file-height="480" /></a><figcaption>Decreasing brightness with depth (underwater photo as example)</figcaption></figure> <p><b>Brightness</b> is an attribute of <a href="/wiki/Visual_perception" title="Visual perception">visual perception</a> in which a source appears to be radiating or reflecting <a href="/wiki/Light" title="Light">light</a>.<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> In other words, brightness is the <a href="/wiki/Perception" title="Perception">perception</a> elicited by the <a href="/wiki/Luminance" title="Luminance">luminance</a> of a visual target. The perception is not linear to luminance, and relies on the context of the viewing environment (for example, see <a href="/wiki/White%27s_illusion" title="White's illusion">White's illusion</a>). </p><p>Brightness is a subjective sensation of an object being observed and one of the <a href="/wiki/Color_appearance_model#Color_appearance_parameters" title="Color appearance model">color appearance parameters</a> of many <a href="/wiki/Color_appearance_model" title="Color appearance model">color appearance models</a>, typically denoted as <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="{\displaystyle Q}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mi>Q</mi> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle Q}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/8752c7023b4b3286800fe3238271bbca681219ed" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.671ex; width:1.838ex; height:2.509ex;" alt="{\displaystyle Q}"></span>. Brightness refers to how much light <i>appears to shine</i> from something. This is a different perception than <a href="/wiki/Lightness" title="Lightness">lightness</a>, which is how light something appears <i>compared to</i> a similarly lit white object.<sup id="cite_ref-2" class="reference"><a href="#cite_note-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup> </p><p>The adjective <i><a href="https://en.wiktionary.org/wiki/bright" class="extiw" title="wikt:bright">bright</a></i> derives from an Old English <i><a href="/wiki/Beorht" class="mw-redirect" title="Beorht">beorht</a></i> with the same meaning via metathesis giving Middle English <i>briht</i>. The word is from a <a href="/wiki/Proto-Germanic" class="mw-redirect" title="Proto-Germanic">Proto-Germanic</a> <i><span title="Proto-Germanic-language text">*<i lang="gem">berhtaz</i></span></i>, ultimately from a <a href="/wiki/Proto-Indo-European_language" title="Proto-Indo-European language">PIE</a> root with a closely related meaning, *<i><span title="Proto-Indo-European-language text" class="Unicode" style="white-space:nowrap;"><span lang="ine">bhereg-</span></span></i> "white, bright". "Brightness" was formerly used as a synonym for the <a href="/wiki/Photometry_(optics)" title="Photometry (optics)">photometric</a> term <i><a href="/wiki/Luminance" title="Luminance">luminance</a></i> and (incorrectly) for the <a href="/wiki/Radiometric" class="mw-redirect" title="Radiometric">radiometric</a> term <i><a href="/wiki/Radiance" title="Radiance">radiance</a></i>. As defined by the US <i>Federal Glossary of Telecommunication Terms</i> (<a href="/wiki/Federal_Standard_1037C" title="Federal Standard 1037C">FS-1037C</a>), "brightness" should now be used only for non-quantitative references to physiological sensations and perceptions of light.<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> Brightness is an antonym of "<a href="https://en.wiktionary.org/wiki/dimness" class="extiw" title="wikt:dimness">dimness</a>" or "<a href="https://en.wiktionary.org/wiki/dullness" class="extiw" title="wikt:dullness">dullness</a>". </p><p>With regard to <a href="/wiki/Star" title="Star">stars</a>, brightness is quantified as <a href="/wiki/Apparent_magnitude" title="Apparent magnitude">apparent magnitude</a> and <a href="/wiki/Absolute_magnitude" title="Absolute magnitude">absolute magnitude</a>. </p><p>Two <a href="/wiki/Solar_symbol" title="Solar symbol">pictograms resembling the Sun</a> with rays are used to represent the settings of <a href="/wiki/Luminance" title="Luminance">luminance</a> in <a href="/wiki/Electronic_visual_display" title="Electronic visual display">display devices</a>. They have been encoded in <a href="/wiki/Unicode" title="Unicode">Unicode</a> since version 6.0 (October 2010) in the Miscellaneous Symbols and Pictographs block under U+1505 as "low brightness symbol" (🔅) and U+1F506 as "high brightness symbol" (🔆).<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> </p><p>The United States <a href="/wiki/Federal_Trade_Commission" title="Federal Trade Commission">Federal Trade Commission</a> (FTC) has assigned an unconventional meaning to brightness when applied to <a href="/wiki/Electric_light" title="Electric light">lamps</a>. When appearing on light bulb packages, brightness means <a href="/wiki/Luminous_flux" title="Luminous flux">luminous flux</a>, while in other contexts it means luminance.<sup id="cite_ref-ftc_5-0" class="reference"><a href="#cite_note-ftc-5"><span class="cite-bracket">[</span>5<span class="cite-bracket">]</span></a></sup> Luminous flux is the total amount of light coming from a source, such as a lighting device. Luminance, the original meaning of brightness, is the amount of light per solid angle coming from an area, such as the sky. The table below shows the standard ways of indicating the amount of light. </p><p><span class="anchor" id="table-si-photometry-units"></span> </p> <table class="wikitable plainrowheaders"> <caption><style data-mw-deduplicate="TemplateStyles:r1045256916">.mw-parser-output .navbar-header{text-align:center;position:relative;white-space:nowrap}.mw-parser-output .navbar-header .navbar{position:absolute;right:0;top:0;margin:0 5px}</style><div class="navbar-header"><span style="font-size:130%;">SI photometry quantities</span><style data-mw-deduplicate="TemplateStyles:r1129693374">.mw-parser-output .hlist dl,.mw-parser-output .hlist ol,.mw-parser-output .hlist ul{margin:0;padding:0}.mw-parser-output .hlist dd,.mw-parser-output .hlist dt,.mw-parser-output .hlist li{margin:0;display:inline}.mw-parser-output .hlist.inline,.mw-parser-output .hlist.inline dl,.mw-parser-output .hlist.inline ol,.mw-parser-output .hlist.inline ul,.mw-parser-output .hlist dl dl,.mw-parser-output .hlist dl ol,.mw-parser-output .hlist dl ul,.mw-parser-output .hlist ol dl,.mw-parser-output .hlist ol ol,.mw-parser-output .hlist ol ul,.mw-parser-output .hlist ul dl,.mw-parser-output .hlist ul ol,.mw-parser-output .hlist ul ul{display:inline}.mw-parser-output .hlist .mw-empty-li{display:none}.mw-parser-output .hlist dt::after{content:": "}.mw-parser-output .hlist dd::after,.mw-parser-output .hlist li::after{content:" · ";font-weight:bold}.mw-parser-output .hlist dd:last-child::after,.mw-parser-output .hlist dt:last-child::after,.mw-parser-output .hlist li:last-child::after{content:none}.mw-parser-output .hlist dd dd:first-child::before,.mw-parser-output .hlist dd dt:first-child::before,.mw-parser-output .hlist dd li:first-child::before,.mw-parser-output .hlist dt dd:first-child::before,.mw-parser-output .hlist dt dt:first-child::before,.mw-parser-output .hlist dt li:first-child::before,.mw-parser-output .hlist li dd:first-child::before,.mw-parser-output .hlist li dt:first-child::before,.mw-parser-output .hlist li li:first-child::before{content:" (";font-weight:normal}.mw-parser-output .hlist dd dd:last-child::after,.mw-parser-output .hlist dd dt:last-child::after,.mw-parser-output .hlist dd li:last-child::after,.mw-parser-output .hlist dt dd:last-child::after,.mw-parser-output .hlist dt dt:last-child::after,.mw-parser-output .hlist dt li:last-child::after,.mw-parser-output .hlist li dd:last-child::after,.mw-parser-output .hlist li dt:last-child::after,.mw-parser-output .hlist li li:last-child::after{content:")";font-weight:normal}.mw-parser-output .hlist ol{counter-reset:listitem}.mw-parser-output .hlist ol>li{counter-increment:listitem}.mw-parser-output .hlist ol>li::before{content:" "counter(listitem)"\a0 "}.mw-parser-output .hlist dd ol>li:first-child::before,.mw-parser-output .hlist dt ol>li:first-child::before,.mw-parser-output .hlist li ol>li:first-child::before{content:" ("counter(listitem)"\a0 "}</style><style data-mw-deduplicate="TemplateStyles:r1239400231">.mw-parser-output .navbar{display:inline;font-size:88%;font-weight:normal}.mw-parser-output .navbar-collapse{float:left;text-align:left}.mw-parser-output .navbar-boxtext{word-spacing:0}.mw-parser-output .navbar ul{display:inline-block;white-space:nowrap;line-height:inherit}.mw-parser-output .navbar-brackets::before{margin-right:-0.125em;content:"[ "}.mw-parser-output .navbar-brackets::after{margin-left:-0.125em;content:" ]"}.mw-parser-output .navbar li{word-spacing:-0.125em}.mw-parser-output .navbar a>span,.mw-parser-output .navbar a>abbr{text-decoration:inherit}.mw-parser-output .navbar-mini abbr{font-variant:small-caps;border-bottom:none;text-decoration:none;cursor:inherit}.mw-parser-output .navbar-ct-full{font-size:114%;margin:0 7em}.mw-parser-output .navbar-ct-mini{font-size:114%;margin:0 4em}html.skin-theme-clientpref-night .mw-parser-output .navbar li a abbr{color:var(--color-base)!important}@media(prefers-color-scheme:dark){html.skin-theme-clientpref-os .mw-parser-output .navbar li a abbr{color:var(--color-base)!important}}@media print{.mw-parser-output .navbar{display:none!important}}</style><div class="navbar plainlinks hlist navbar-mini"><ul><li class="nv-view"><a href="/wiki/Template:SI_light_units" title="Template:SI light units"><abbr title="View this template">v</abbr></a></li><li class="nv-talk"><a href="/wiki/Template_talk:SI_light_units" title="Template talk:SI light units"><abbr title="Discuss this template">t</abbr></a></li><li class="nv-edit"><a href="/wiki/Special:EditPage/Template:SI_light_units" title="Special:EditPage/Template:SI light units"><abbr title="Edit this template">e</abbr></a></li></ul></div></div> </caption> <tbody><tr> <th scope="col" colspan="2">Quantity </th> <th scope="col" colspan="2">Unit </th> <th scope="col" rowspan="2">Dimension<br /><sup id="cite_ref-note-dimension-symbol_6-0" class="reference"><a href="#cite_note-note-dimension-symbol-6"><span class="cite-bracket">[</span>nb 1<span class="cite-bracket">]</span></a></sup> </th> <th scope="col" rowspan="2">Notes </th></tr> <tr> <th scope="col">Name </th> <th scope="col">Symbol<sup id="cite_ref-note-suffix-v_7-0" class="reference"><a href="#cite_note-note-suffix-v-7"><span class="cite-bracket">[</span>nb 2<span class="cite-bracket">]</span></a></sup> </th> <th scope="col">Name </th> <th scope="col">Symbol </th></tr> <tr> <th scope="row"><a href="/wiki/Luminous_energy" title="Luminous energy">Luminous energy</a> </th> <td><span class="texhtml"><i>Q</i><sub>v</sub></span><sup id="cite_ref-note-alternative-symbol-photometric_8-0" class="reference"><a href="#cite_note-note-alternative-symbol-photometric-8"><span class="cite-bracket">[</span>nb 3<span class="cite-bracket">]</span></a></sup> </td> <td><a href="/wiki/Lumen_second" title="Lumen second">lumen second</a> </td> <td><a href="/wiki/Lumen_(unit)" title="Lumen (unit)">lm</a>⋅s </td> <td><b>T</b>⋅<b>J</b> </td> <td>The lumen second is sometimes called the <i>talbot</i>. </td></tr> <tr> <th scope="row"><a href="/wiki/Luminous_flux" title="Luminous flux">Luminous flux</a>, luminous power </th> <td><span class="texhtml">Φ<sub><a href="/wiki/Luminosity_function" class="mw-redirect" title="Luminosity function">v</a></sub></span><sup id="cite_ref-note-alternative-symbol-photometric_8-1" class="reference"><a href="#cite_note-note-alternative-symbol-photometric-8"><span class="cite-bracket">[</span>nb 3<span class="cite-bracket">]</span></a></sup> </td> <td><a href="/wiki/Lumen_(unit)" title="Lumen (unit)">lumen</a> (= candela <a href="/wiki/Steradian" title="Steradian">steradian</a>) </td> <td>lm (= cd⋅sr) </td> <td><b>J</b> </td> <td>Luminous energy per unit time </td></tr> <tr> <th scope="row"><a href="/wiki/Luminous_intensity" title="Luminous intensity">Luminous intensity</a> </th> <td><span class="texhtml"><i>I</i><sub>v</sub></span> </td> <td><a href="/wiki/Candela" title="Candela">candela</a> (= lumen per steradian) </td> <td><a href="/wiki/Candela" title="Candela">cd</a> (= lm/sr) </td> <td><b>J</b> </td> <td>Luminous flux per unit <a href="/wiki/Solid_angle" title="Solid angle">solid angle</a> </td></tr> <tr> <th scope="row"><a href="/wiki/Luminance" title="Luminance">Luminance</a> </th> <td><span class="texhtml"><i>L</i><sub>v</sub></span> </td> <td><a href="/wiki/Candela_per_square_metre" title="Candela per square metre">candela per square metre</a> </td> <td>cd/m<sup>2</sup> (= lm/(sr⋅m<sup>2</sup>)) </td> <td><b>L</b><sup>−2</sup>⋅<b>J</b> </td> <td>Luminous flux per unit solid angle per unit <i>projected</i> source area. The candela per square metre is sometimes called the <i><a href="/wiki/Nit_(unit)" class="mw-redirect" title="Nit (unit)">nit</a></i>. </td></tr> <tr> <th scope="row"><a href="/wiki/Illuminance" title="Illuminance">Illuminance</a> </th> <td><span class="texhtml"><i>E</i><sub>v</sub></span> </td> <td><a href="/wiki/Lux" title="Lux">lux</a> (= lumen per square metre) </td> <td><a href="/wiki/Lux" title="Lux">lx</a> (= lm/m<sup>2</sup>) </td> <td><b>L</b><sup>−2</sup>⋅<b>J</b> </td> <td>Luminous flux <i>incident</i> on a surface </td></tr> <tr> <th scope="row"><a href="/wiki/Luminous_exitance" class="mw-redirect" title="Luminous exitance">Luminous exitance</a>, luminous emittance </th> <td><span class="texhtml"><i>M</i><sub>v</sub></span> </td> <td>lumen per square metre </td> <td>lm/m<sup>2</sup> </td> <td><b>L</b><sup>−2</sup>⋅<b>J</b> </td> <td>Luminous flux <i>emitted</i> from a surface </td></tr> <tr> <th scope="row"><a href="/wiki/Luminous_exposure" class="mw-redirect" title="Luminous exposure">Luminous exposure</a> </th> <td><span class="texhtml"><i>H</i><sub>v</sub></span> </td> <td><a href="/wiki/Lux_second" class="mw-redirect" title="Lux second">lux second</a> </td> <td>lx⋅s </td> <td><b>L</b><sup>−2</sup>⋅<b>T</b>⋅<b>J</b> </td> <td>Time-integrated illuminance </td></tr> <tr> <th scope="row">Luminous energy density </th> <td><span class="texhtml"><i>ω</i><sub>v</sub></span> </td> <td>lumen second per cubic metre </td> <td>lm⋅s/m<sup>3</sup> </td> <td><b>L</b><sup>−3</sup>⋅<b>T</b>⋅<b>J</b> </td> <td> </td></tr> <tr> <th scope="row"><a href="/wiki/Luminous_efficacy" title="Luminous efficacy">Luminous efficacy</a> (of radiation) </th> <td><span class="texhtml"><i>K</i></span> </td> <td>lumen per <a href="/wiki/Watt" title="Watt">watt</a> </td> <td>lm/<a href="/wiki/Watt" title="Watt">W</a> </td> <td><b>M</b><sup>−1</sup>⋅<b>L</b><sup>−2</sup>⋅<b>T</b><sup>3</sup>⋅<b>J</b> </td> <td>Ratio of luminous flux to <a href="/wiki/Radiant_flux" title="Radiant flux">radiant flux</a> </td></tr> <tr> <th scope="row"><a href="/wiki/Luminous_efficacy" title="Luminous efficacy">Luminous efficacy</a> (of a source) </th> <td><span class="texhtml mvar" style="font-style:italic;">η</span><sup id="cite_ref-note-alternative-symbol-photometric_8-2" class="reference"><a href="#cite_note-note-alternative-symbol-photometric-8"><span class="cite-bracket">[</span>nb 3<span class="cite-bracket">]</span></a></sup> </td> <td>lumen per <a href="/wiki/Watt" title="Watt">watt</a> </td> <td>lm/<a href="/wiki/Watt" title="Watt">W</a> </td> <td><b>M</b><sup>−1</sup>⋅<b>L</b><sup>−2</sup>⋅<b>T</b><sup>3</sup>⋅<b>J</b> </td> <td>Ratio of luminous flux to power consumption </td></tr> <tr> <th scope="row"><a href="/wiki/Luminous_efficiency" class="mw-redirect" title="Luminous efficiency">Luminous efficiency</a>, luminous coefficient </th> <td><span class="texhtml mvar" style="font-style:italic;">V</span> </td> <td> </td> <td> </td> <td><b>1</b> </td> <td>Luminous efficacy normalized by the maximum possible efficacy </td></tr> <tr> <td style="text-align:center;" colspan="6">See also: <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1129693374"><div class="hlist inline"><ul><li><a href="/wiki/SI" class="mw-redirect" title="SI">SI</a></li><li><a href="/wiki/Photometry_(optics)" title="Photometry (optics)">Photometry</a></li><li><a href="/wiki/Radiometry" title="Radiometry">Radiometry</a></li></ul></div> </td></tr></tbody></table><style data-mw-deduplicate="TemplateStyles:r1239543626">.mw-parser-output .reflist{margin-bottom:0.5em;list-style-type:decimal}@media screen{.mw-parser-output .reflist{font-size:90%}}.mw-parser-output .reflist .references{font-size:100%;margin-bottom:0;list-style-type:inherit}.mw-parser-output .reflist-columns-2{column-width:30em}.mw-parser-output .reflist-columns-3{column-width:25em}.mw-parser-output .reflist-columns{margin-top:0.3em}.mw-parser-output .reflist-columns ol{margin-top:0}.mw-parser-output .reflist-columns li{page-break-inside:avoid;break-inside:avoid-column}.mw-parser-output .reflist-upper-alpha{list-style-type:upper-alpha}.mw-parser-output .reflist-upper-roman{list-style-type:upper-roman}.mw-parser-output .reflist-lower-alpha{list-style-type:lower-alpha}.mw-parser-output .reflist-lower-greek{list-style-type:lower-greek}.mw-parser-output .reflist-lower-roman{list-style-type:lower-roman}</style><div class="reflist"> <div class="mw-references-wrap"><ol class="references"> <li id="cite_note-note-dimension-symbol-6"><span class="mw-cite-backlink"><b><a href="#cite_ref-note-dimension-symbol_6-0">^</a></b></span> <span class="reference-text">The symbols in this column denote <a href="/wiki/Dimensional_analysis#Definition" title="Dimensional analysis">dimensions</a>; "<b>L</b>", "<b>T</b>" and "<b>J</b>" are for length, time and luminous intensity respectively, not the symbols for the <a href="/wiki/Unit_of_measurement" title="Unit of measurement">units</a> litre, tesla and joule.</span> </li> <li id="cite_note-note-suffix-v-7"><span class="mw-cite-backlink"><b><a href="#cite_ref-note-suffix-v_7-0">^</a></b></span> <span class="reference-text"><a href="/wiki/Standards_organization" title="Standards organization">Standards organizations</a> recommend that photometric quantities be denoted with a subscript "v" (for "visual") to avoid confusion with radiometric or <a href="/wiki/Photon" title="Photon">photon</a> quantities. For example: <i>USA Standard Letter Symbols for Illuminating Engineering</i> USAS Z7.1-1967, Y10.18-1967</span> </li> <li id="cite_note-note-alternative-symbol-photometric-8"><span class="mw-cite-backlink">^ <a href="#cite_ref-note-alternative-symbol-photometric_8-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-note-alternative-symbol-photometric_8-1"><sup><i><b>b</b></i></sup></a> <a href="#cite_ref-note-alternative-symbol-photometric_8-2"><sup><i><b>c</b></i></sup></a></span> <span class="reference-text">Alternative symbols sometimes seen: <span class="texhtml mvar" style="font-style:italic;">W</span> for luminous energy, <span class="texhtml mvar" style="font-style:italic;">P</span> or <span class="texhtml mvar" style="font-style:italic;">F</span> for luminous flux, and <span class="texhtml mvar" style="font-style:italic;">ρ</span> for luminous efficacy of a source.</span> </li> </ol></div></div> <div class="mw-heading mw-heading2"><h2 id="See_also">See also</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Brightness&action=edit&section=1" title="Edit section: See also"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <ul><li><a href="/wiki/Luma_(video)" title="Luma (video)">Luma (video)</a></li> <li><a href="/wiki/Luminance_(relative)" class="mw-redirect" title="Luminance (relative)">Luminance (relative)</a></li> <li><a href="/wiki/Luminosity" title="Luminosity">Luminosity</a></li></ul> <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=Brightness&action=edit&section=2" title="Edit section: References"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1239543626"><div class="reflist"> <div class="mw-references-wrap"><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.merriam-webster.com/dictionary/bright">Bright Definition & Meaning</a>", Merriam-Webster Dictionary.</span> </li> <li id="cite_note-2"><span class="mw-cite-backlink"><b><a href="#cite_ref-2">^</a></b></span> <span class="reference-text">Robert William Gainer Hunt: <i>Some comments on using the CIECAM97s colour-appearance model</i></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">“<a rel="nofollow" class="external text" href="http://www.its.bldrdoc.gov/fs-1037/dir-005/_0719.htm">Brightness</a>” in Federal Standard 1037C, the <i>Federal Glossary of Telecommunication Terms</i> (1996)</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 class="citation web cs1"><a rel="nofollow" class="external text" href="https://unicode.org/charts/PDF/U1F300.pdf">"Miscellaneous Symbols and Pictographs"</a> <span class="cs1-format">(PDF)</span>. Unicode Consortium. 2023.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=Miscellaneous+Symbols+and+Pictographs&rft.pub=Unicode+Consortium&rft.date=2023&rft_id=https%3A%2F%2Funicode.org%2Fcharts%2FPDF%2FU1F300.pdf&rfr_id=info%3Asid%2Fen.wikipedia.org%3ABrightness" class="Z3988"></span></span> </li> <li id="cite_note-ftc-5"><span class="mw-cite-backlink"><b><a href="#cite_ref-ftc_5-0">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://www.consumer.ftc.gov/articles/0164-shopping-light-bulbs">"Shopping for Light Bulbs"</a>. United States <a href="/wiki/Federal_Trade_Commission" title="Federal Trade Commission">Federal Trade Commission</a><span class="reference-accessdate">. Retrieved <span class="nowrap">March 13,</span> 2017</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=Shopping+for+Light+Bulbs&rft.pub=United+States+Federal+Trade+Commission&rft_id=https%3A%2F%2Fwww.consumer.ftc.gov%2Farticles%2F0164-shopping-light-bulbs&rfr_id=info%3Asid%2Fen.wikipedia.org%3ABrightness" class="Z3988"></span></span> </li> </ol></div></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=Brightness&action=edit&section=3" title="Edit section: External links"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p><span class="noviewer" typeof="mw:File"><a href="/wiki/File:Commons-logo.svg" class="mw-file-description"><img alt="" src="//upload.wikimedia.org/wikipedia/en/thumb/4/4a/Commons-logo.svg/12px-Commons-logo.svg.png" decoding="async" 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Wiktionary, the free dictionary.</div></div> </div> <ul><li><a rel="nofollow" class="external text" href="http://www.poynton.com/ColorFAQ.html">Poynton's Color FAQ</a></li></ul> <div class="navbox-styles"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1129693374"><style data-mw-deduplicate="TemplateStyles:r1236075235">.mw-parser-output .navbox{box-sizing:border-box;border:1px solid #a2a9b1;width:100%;clear:both;font-size:88%;text-align:center;padding:1px;margin:1em auto 0}.mw-parser-output .navbox .navbox{margin-top:0}.mw-parser-output .navbox+.navbox,.mw-parser-output .navbox+.navbox-styles+.navbox{margin-top:-1px}.mw-parser-output .navbox-inner,.mw-parser-output .navbox-subgroup{width:100%}.mw-parser-output .navbox-group,.mw-parser-output .navbox-title,.mw-parser-output .navbox-abovebelow{padding:0.25em 1em;line-height:1.5em;text-align:center}.mw-parser-output .navbox-group{white-space:nowrap;text-align:right}.mw-parser-output .navbox,.mw-parser-output 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