What is Retina Display

Technology Zones - Retina Display is a brand name used by Apple for liquid crystal displays which they claim to have a high enough pixel density that the human eye is unable to notice pixelation at a typical viewing distance. The term is used for several Apple products, including the iPhone, iPod Touch, iPad, and MacBook Pro. As the typical viewing distance would be different depending on each device's usage, the pixels per inch claimed as retina quality can be different for the smallest devices (326, iPhone and iPod Touch): greater than the mid-sized devices (264, iPad) and greater than the larger devices (220, MacBook Pro).
The displays are manufactured by different suppliers. Currently, the iPad's display comes from the same suppliers Samsung use whilst Macbook Pro displays are mostly made by LG's suppliers, along with the iPhone and iPod Touch displays. Apple has applied to register the term "Retina" as a trademark in regard to computers and mobile devices with the United States Patent and Trademark Office, Canadian Intellectual Property Office, and in Jamaica.


Technical information 

Apple markets the following devices as having retina displays.

Model	PPI (pixels per inch)	ppcm (pixels per cm)	Resolution	Typical Viewing Distance (in/cm)	Single Pixel Visual angle (arcminutes)
iPhone 4/4S and iPod Touch (4th generation)	326	128	960×640	10 inches (25 cm)	1.1
iPhone 5 and iPod Touch (5th generation)			1136×640
iPad (3rd generation)	264	104	2048×1536	15 inches (38 cm)	0.87
MacBook Pro (3rd generation)	220	87	2880×1800	20 inches (51 cm)	0.78

Criticism 

According to Raymond Soneira, president of DisplayMate Technologies, the resolution of the actual human retina is higher than claimed by Apple, working out to 477 pixels per inch at 12 inches (305 mm) from the eye. Phil Plait of Bad Astronomy wrote a response saying that "if you have [better than 20/20] eyesight, then at one foot away the iPhone 4's pixels are resolved. The picture will look pixellated. If you have average eyesight [20/20 vision], the picture will look just fine," and concluded, "So in my opinion, what Jobs said was fine. Soneira, while technically correct, was being picky." Retinal neuroscientist Bryan Jones using a similar but more detailed analysis, came to a similar conclusion on his blog, stating "...I’d find Apple’s claims stand up to what the human eye can perceive."