Editing Plasma display (section)

=== Contrast ratio ===

[[Contrast ratio]] is the difference between the brightest and darkest parts of an image, measured in discrete steps, at any given moment. Generally, the higher the contrast ratio, the more realistic the image is (though the "realism" of an image depends on many factors including color accuracy, luminance linearity, and spatial linearity). Contrast ratios for plasma displays are often advertised as high as 5,000,000:1.<ref>{{cite web|url=http://www.panasonic.net/avc/viera/us2010/product/comparison_plasma.html|title=Official Panasonic Store - Research and Buy Cameras, Headphones, Appliances, Shavers, Beauty products, and More|website=www.panasonic.net|access-date=2010-02-25|archive-url=https://web.archive.org/web/20111002124729/http://www.panasonic.net/avc/viera/us2010/product/comparison_plasma.html|archive-date=2011-10-02|url-status=dead}}</ref> On the surface, this is a significant advantage of plasma over most other current display technologies, a notable exception being [[organic light-emitting diode]]. Although there are no industry-wide guidelines for reporting contrast ratio, most manufacturers follow either the ANSI standard or perform a full-on-full-off test. The ANSI standard uses a checkered test pattern whereby the darkest blacks and the lightest whites are simultaneously measured, yielding the most accurate "real-world" ratings. In contrast, a full-on-full-off test measures the ratio using a pure black screen and a pure white screen, which gives higher values but does not represent a typical viewing scenario. Some displays, using many different technologies, have some "leakage" of light, through either optical or electronic means, from lit pixels to adjacent pixels so that dark pixels that are near bright ones appear less dark than they do during a full-off display. Manufacturers can further artificially improve the reported contrast ratio by increasing the contrast and brightness settings to achieve the highest test values. However, a contrast ratio generated by this method is misleading, as content would be essentially unwatchable at such settings.<ref>[[Google Book Search|Google books]] – [https://books.google.com/books?id=oM2mWjnIVjcC&dq=plasma+display+Contrast+ratio&pg=PA21 Digital Signage Broadcasting By Lars-Ingemar Lundström] {{Webarchive|url=https://web.archive.org/web/20230413013313/https://books.google.com/books?id=oM2mWjnIVjcC&dq=plasma+display+Contrast+ratio&pg=PA21 |date=2023-04-13 }}</ref><ref>[[Google Book Search|Google books]] – [https://books.google.com/books?id=pPMursVsxlMC&dq=plasma+display+Contrast+ratio&pg=PA768 Instrument Engineers' Handbook: Process control and optimization By Béla G. Lipták] {{Webarchive|url=https://web.archive.org/web/20230413013313/https://books.google.com/books?id=pPMursVsxlMC&dq=plasma+display+Contrast+ratio&pg=PA768 |date=2023-04-13 }}</ref><ref>[[Google Book Search|Google books]] – [https://books.google.com/books?id=jykvlTCoksMC&dq=plasma+display+Contrast+ratio&pg=PT191 Computers, Software Engineering, and Digital Devices By Richard C. Dorf] {{Webarchive|url=https://web.archive.org/web/20230413013313/https://books.google.com/books?id=jykvlTCoksMC&dq=plasma+display+Contrast+ratio&pg=PT191 |date=2023-04-13 }}</ref>

Each cell on a plasma display must be precharged before it is lit, otherwise the cell would not respond quickly enough. Precharging normally increases power consumption, so energy recovery mechanisms may be in place to avoid an increase in power consumption.<ref>{{cite web|url=https://patents.google.com/patent/KR100907390B1/en|title=Plasma display device|access-date=2020-11-01|archive-date=2021-10-24|archive-url=https://web.archive.org/web/20211024161759/https://patents.google.com/patent/KR100907390B1/en|url-status=live}}</ref><ref>{{cite web|url=https://patents.google.com/patent/US4247854|title=Gas panel with improved circuit for display operation|access-date=2020-11-01|archive-date=2021-10-24|archive-url=https://web.archive.org/web/20211024161759/https://patents.google.com/patent/US4247854|url-status=live}}</ref><ref>{{Cite web|url=https://patents.google.com/patent/US8138993B2/en|title=Control of a plasma display panel|access-date=2020-11-01|archive-date=2021-10-24|archive-url=https://web.archive.org/web/20211024161801/https://patents.google.com/patent/US8138993B2/en|url-status=live}}</ref> This precharging means the cells cannot achieve a true black,<ref>{{cite web|url = https://www.tvtechnology.com/news/replacing-the-crt-iii|title = Replacing the CRT III|date = 2 November 2008|access-date = 1 November 2020|archive-date = 2 December 2020|archive-url = https://web.archive.org/web/20201202160320/https://www.tvtechnology.com/news/replacing-the-crt-iii|url-status = live}}</ref> whereas an LED backlit LCD panel can actually turn off parts of the backlight, in "spots" or "patches" (this technique, however, does not prevent the large accumulated passive light of adjacent lamps, and the reflection media, from returning values from within the panel). Some manufacturers have reduced the precharge and the associated background glow, to the point where black levels on modern plasmas are starting to become close to some high-end CRTs Sony and Mitsubishi produced ten years before the comparable plasma displays. With an LCD, black pixels are generated by a light polarization method; many panels are unable to completely block the underlying backlight. More recent LCD panels using [[LED]] illumination can automatically reduce the backlighting on darker scenes, though this method cannot be used in high-contrast scenes, leaving some light showing from black parts of an image with bright parts, such as (at the extreme) a solid black screen with one fine intense bright line. This is called a "halo" effect which has been minimized on newer LED-backlit LCDs with local dimming. Edgelit models cannot compete with this as the light is reflected via a light guide to distribute the light behind the panel.<ref name=PDP2/><ref name=PDP1/><ref name=PDP3/>

Plasma displays are capable of producing deeper blacks than LCD allowing for a superior contrast ratio.<ref name=PDP2/><ref name=PDP1>{{Cite web|url=https://www.crutchfield.com/learn/learningcenter/home/tv_flatpanel.html|title=LED-LCD vs. Plasma|website=Crutchfield|access-date=2023-06-19|archive-date=2021-05-31|archive-url=https://web.archive.org/web/20210531091601/https://www.crutchfield.com/learn/learningcenter/home/tv_flatpanel.html|url-status=live}}</ref><ref name=PDP3>HomeTheaterMag.com – [http://www.hometheatermag.com/advicefromtheexperts/407plasmavlcd/ Plasma Vs. LCD] {{Webarchive|url=https://web.archive.org/web/20090907125218/http://www.hometheatermag.com/advicefromtheexperts/407plasmavlcd/ |date=2009-09-07 }}</ref>

Earlier generation displays (circa 2006 and prior) had phosphors that lost luminosity over time, resulting in gradual decline of absolute image brightness. Newer models have advertised lifespans exceeding 100,000 hours (11 years), far longer than older [[cathode-ray tube|CRT]]s.<ref name=PDPlife/><ref name=PDP3/>