Retina Display - The name given by Apple to the high-resolution screen technology introduced on the iPhone 4 in June 2010. There is no single screen resolution that make something a Retina Display. Rather, something is a Retina Display when it offers a density of pixels above 163 pixels per inch.
Retina Display is designed to smooth the jagged edges of pixels are provide a higher-quality image than previously available on mobile devices. Apple claims that it's resolution is so good that it makes it impossible for the human eye to distinguish individual pixels (given variables such as distance from the screen, etc). The effects of the display technology are noticeable in many uses, but especially in text, where font edges are curves are substantially smoother than on previous display technologies.
Retina Display's image quality derives from a number of factors:
- A greater density of the pixels that make up the device's screen
- Higher contrast ratio than previous models for brighter whites and deeper blacks
- In-Plane Switching (IPS) technology to improve viewing angles
- Chemically treated glass over the screen and LED backlighting to improve the quality of the image
The Retina Display, as used on the iPhone 4 and 4th-generation iPod touch, offers a resolution of 960 x 640 pixels. Since both devices have 3.5-inch diagonal screens, this means they offer 326 pixels per inch.
It's this resolution--326 pixels per inch--that Apple initially claimed was the threshold for the human eye distinguishing pixels. The resolution was achieved on a relatively small screen thanks to pixels that are just 78 micrometers wide, according to Apple.
As other devices also gained Retina Displays, 326 pixels per inch was no longer the standard. For instance, the iPad mini has a 1024 x 768 screen which, at its 7.9-inch size, translates to 163 pixels per inch. That, too, is a Retina Display screen.
Some experts disagree with Apple's claims that Retina Display actually offers the same resolution as the human eye, pointing out that the iPhone would need varying numbers of pixels per inch, depending on how close it is to the eye, to mimic the human retina.
Use in Apple Products
Retina Displays are available on the following Apple products: