Editing Pixel density (section)

{{Short description|Screen resolution measured in pixels per length}}
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'''Pixels per inch''' ('''ppi''') and '''pixels per centimetre''' ('''ppcm''' or '''pixels/cm''') are measurements of the '''pixel density''' of an electronic image device, such as a [[computer displays|computer monitor]] or [[television]] display, or image digitizing device such as a [[digital photography|camera]] or [[image scanner]]. Horizontal and vertical density are usually the same, as most devices have [[square pixel]]s, but differ on devices that have non-square pixels. Pixel density is not the same as {{nowrap|[[Display resolution|resolution]]{{hsp}}{{mdash}}}}{{hsp}}where the former describes the amount of detail on a physical surface or device, the latter describes the amount of pixel information regardless of its scale. Considered in another way, a [[pixel]] has no inherent size or unit (a pixel is actually a sample), but when it is printed, displayed, or scanned, then the pixel has both a physical size (dimension) and a pixel density (ppi).<ref>{{cite web|title=A Pixel Is Not A Little Square|url=http://alvyray.com/Memos/CG/Microsoft/6_pixel.pdf|author=Alvy Ray Smith|date=11 Nov 1996}}</ref>