PPI = total number of pixels vertically / size of screen in inches vertically PPI = total number of pixels horizontally / size of screen in inches horizontally Pixel density is equal to display's native resolution divided by screen size in inches and can be expressed as either of two following formulas: The higher the pixel density of the display, the sharper and crisper are text and images being displayed. Pixel density determines how high is the definition of the display. Historically term dpi has been used for printers & scanners and even though for electronic displays term dot translates to pixel and therefore ppi would be more correct term, today both terms are used interchangeably. Value of pixel density is expressed as dpi(dots per inch) or ppi(pixels per inch). Pixel density is an attribute of a display device measured as number of device pixels within one inch of screen space, either in horizontal or vertical direction. Reference pixel size varies with typical intended user device viewing distance, it becomes larger if the viewing distance increases(TVs) or smaller if viewing distance decreases as in case of handheld devices such as smartphones or tablets. Visual angle is therefore about 0.0213 degrees and at arm’s length distance of reader from display, one reference pixel corresponds to about 0.26 mm (1/96 inch). Reference pixel gives physical size to abstract notion of pixel as point of visual information.Īs defined by W3C(World Wide Web Consortium), reference pixel is the visual angle of one pixel on a display device with a pixel density of 96dpi(classic desktop monitor) and a distance from the reader of nominal arm’s length of 28 inches. Thanks to human perception of colors, combinations of different shades of these three primary colors give single screen pixel way to reproduce all other colors in color gamut.Ĭontemporary smartphones and tablets may use different number of subpixels per pixel( PenTile matrices) but principle stays the same. Pixel(picture element) is a smallest controllable element of a display device and therefore pixels are basic building blocks of any image you see on screen.Įach pixel is divided into three subpixels, each showing one color of varying intensity/brightness: red, green and blue(RGB). Some standard display resolutions and their market names/acronyms:ġ280 x 720 (720p, HD, HD Ready, Standard HD)Ģ560 x 1440 (1440p, Wide Quad HD, Quad HD, WQHD, QHD)Īspect ratio of a display device is a ratio between the width and the height of the screen. Furthermore, more viewable content can fit onto a higher resolution screen. The higher the display resolution is, the sharper and clearer displayed content can be because a higher resolution monitor will be made up of more pixels than a lower resolution monitor. It is usually noted in a format of width x height, for instance: 1920 x 1080 means the width is 1920 pixels and the height is 1080 pixels which in this case would give total of 2,073,600 pixels on screen. See the iPad 3 and later, iPad Air and later, iPad mini, iPhone, iPhone 5, and iPhone 6 for devices offering a Retina display.Screen or display resolution of electronic visual display device is the number of individual pixels in each axis that can be displayed on screen. The higher resolution is expected for devices that are expected to be used closer to your face. Other smaller devices have standardized on the 326 ppi for all iPhones except the S models which increased the ppi to 401 primarily to reach the standard F HD resolution. However, the iPad mini has a 326 ppi resolution which matches the pixel size of a 9.7" Apple iPad. Some claim that they get headaches on any other type of display while others say they can't tell much difference in actual use.Īpple has standardize its iPads at 264 ppi. Users will differ on whether it is useful, important, or perhaps absolutely necessary.
The term "Retina" when applied to computer display is a registered trademark of Apple. See also The reference pixel on W3C site Legality However there is no question that Apple retina display are high resolution. To understand if the answer is truly a retina display you need to understand visual acuity.
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