Retina Display

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This article is about the HD screens of Apple products. It is not to be confused with Virtual retinal display.

Retina Display, or later Retina HD Display on release of the iPhone 6/6 Plus in September 2014, and Retina 5K Display on release of the October 2014 iMac (marketed by Apple with a lowercase 'D' as Retina display, Retina HD display, or Retina 5K display) are brand names used by Apple for screens that have a higher pixel density than their previous models.[1] The terms are used for several Apple products, including the iPhone, iPod Touch, iPad, MacBook Pro, iPad Mini, iPad Air and iMac.[2]

Because the typical viewing distance is different, depending on each device's use, the pixels per inch claimed to be of Retina quality can differ, depending on the size of the display, with higher PPI for smaller displays and lower PPI for larger displays. Later device versions have an even higher quality improvement, either counted by an increase in the PPI (the iPhone 6 Plus) and/or by an increase in the number of pixels (the iPhone 6/6 Plus, and iMac With Retina 5K Display), thus Apple using the moniker "Retina HD Display" or "Retina 5K Display":

Many other manufacturers' displays have similar or higher pixel densities. When an Apple product has a Retina Display, each user interface widget is doubled in width and height to compensate for the smaller pixels. Apple calls this mode HiDPI mode. 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.[3][4] On November 27, 2012 the US Patent and Trademark office approved Apple's application and "Retina" is now a registered trademark for computer equipment.

Models[edit]

The displays are manufactured worldwide by different suppliers. Currently, the iPad's display comes from LG Display,[5] while the Macbook Pro, iPhone, and iPod Touch displays are made by LG[6] and Japan Display Inc.[7] There was a shift of display technology from twisted nematic (TN) liquid-crystal displays (LCDs) to in-plane switching (IPS) LCDs starting with the iPhone 4 models.

Apple markets the following devices as having a Retina Display, Retina HD Display, or Retina 5K Display:

Model[8][9][10][11][12] Marketing name PPI (pixels per inch) PPCM (pixels per cm) PPD (pixels per degree) Resolution Number of pixels Typical viewing distance (in/cm)
iPhone 4/4S and iPod Touch (4th generation) Retina Display 326 128 57 960×640 614,400 10 inches (25 cm)
iPhone 5/5C/5S and iPod Touch (5th generation) 1136×640 727,040
iPhone 6 Retina HD Display 1334×750 1,000,500
iPhone 6 Plus 401 157 70 1920×1080 2,073,600
iPad (3rd/4th generation/iPad Air) Retina Display 264 105 69 2048×1536 3,145,728 15 inches (38 cm)
iPad Mini (2nd generation) 326 128 85
MacBook Pro (3rd generation) 15" 220 87 77 2880×1800 5,184,000 20 inches (51 cm)
MacBook Pro (3rd generation) 13" 227 89 79 2560×1600 4,096,000
iMac (Intel-based) Slim Unibody iMac 27" Retina 5K display 218 86 76 5120x2880 14,745,600

Technical definition[edit]

When introducing the iPhone 4, Steve Jobs said the amount of pixels needed for a Retina Display is about 300 PPI for a device held 10 to 12 inches from the eye.[1] One way of expressing this as a unit is pixels-per-degree (PPD) which takes into account both the screen resolution and the distance from which the device is viewed. Based on Jobs' magic number of 300, the threshold for a Retina Display starts at a the PPD value of 53 PPD. 53 PPD means that a tall skinny triangle with a height equal to the viewing distance and a top angle of one degree will have a base on the device's screen that covers 53 pixels. Any display's viewing quality (from phone displays to huge projectors) can be described with this size-independent universal parameter. Note that the PPD parameter is not an intrinsic parameter of the display itself, unlike absolute pixel resolution (e.g. 1024×800 pixels) or relative pixel density (e.g. 72 PPI), but is dependent on the distance between the display and the eye of the person (or lens of the device) viewing the display; moving the eye closer to the display reduces the PPD, and moving away from it increases the PPD in proportion to the distance. It can be calculated by the formula

 2 d r \tan(0.5^\circ)

where d is the distance to the screen and r is the resolution of the screen in pixels per unit length.

In practice, thus far Apple has converted a device's display to Retina by doubling the number of pixels in each direction, quadrupling the total resolution. This increase creates a sharper interface at the same physical dimensions. The sole exception to this has been the iPhone 6 Plus, which renders its display at triple the number of pixels in each direction, before down-sampling to a 1080P resolution.

Criticism[edit]

Raymond Soneira, president of DisplayMate Technologies, has challenged Apple's claim. He says that the physiology of the human retina is such that there must be at least 477 pixels per inch in a pixelated display for the pixels to become imperceptible to the human eye at a distance of 12 inches (305 mm).[13] The astronomer and science blogger Phil Plait notes, however, that, "if you have [better than 20/20] eyesight, then at one foot away the iPhone 4S's pixels are resolved. The picture will look pixelated. If you have average eyesight [20/20 vision], the picture will look just fine... So in my opinion, what Jobs said was fine. Soneira, while technically correct, was being picky."[14] Shortly after Soneira's challenge, the Boys of Tech podcast published their own analysis[15] and concluded that Soneira's claim was invalid and that Jobs' claim was correct. This was primarily because Soneira misinterpreted the manner in which the acuity of the human eye can be tested. The retinal neuroscientist Bryan Jones offers a similar analysis of more detail and comes to a similar conclusion: "I'd find Apple’s claims stand up to what the human eye can perceive."[16]

On the topic of 20/20 vision, Apple fan website CultOfMac said "most research suggests that normal vision is actually much better than 20/20. In fact, people with normal vision usually won't see their eyesight degrade to 20/20 until they are 60 or 70 years of age"[17] (confirmed by vision testing experts Precision Vision).[18] CultOfMac also noted that people do not always view displays at a constant distance, and will sometimes move closer, at which point the display could no longer be classed as Retina.[17]

See also[edit]

References[edit]

  1. ^ a b "NPR Live Blog of iPhone 4 Introduction". NPR. June 7, 2010. Retrieved June 4, 2014. 
  2. ^ "Apple – Learn about the Retina display". Retrieved June 21, 2010. 
  3. ^ United States Patent and Trademark Office. "Latest Status Info – Serial Number 85056807". Trademark Applications and Registrations Retrieval. Retrieved June 19, 2012.  Claims priority filing date with respect to prior application in Jamaica.
  4. ^ Canadian Intellectual Property Office. "Canadian Trade-Mark Data – Application Number 1483982". Canadian Trade-marks Database. Retrieved June 19, 2012.  Also cites prior application in Jamaica.
  5. ^ "Why Samsung makes Retina Displays – but not for its own tablets". Wired magazine. April 4, 2012. Retrieved June 4, 2013. "If you haven't yet laid eyes on the new iPad's screen, you must. "Sharp" doesn't begin to describe Apple's upgrade in display quality. But here's the kicker: Samsung, a company firmly aligned with Android and one of Apple's largest competitors in the mobile space, is manufacturing the new iPad's flagship feature." 
  6. ^ "iFixit Teardown". iFixit. Retrieved July 9, 2012. 
  7. ^ "News related to IPO of Japan Display Inc.". March 19, 2014. Retrieved March 20, 2014. 
  8. ^ "Apple – iPod Touch – Technical Specifications". 
  9. ^ "Apple – iPhone – Technical Specifications". 
  10. ^ "Apple – iPad – Technical Specifications". 
  11. ^ "Apple – MacBook Pro – Technical Specifications". 
  12. ^ "Apple – iMac – Technical Specifications". 
  13. ^ "Analyst challenges Apple's iPhone 4S 'Retina Display' claims". June 9, 2010. Retrieved June 10, 2010. 
  14. ^ "Resolving the iPhone resolution". June 21, 2010. Retrieved June 21, 2010. 
  15. ^ "iPhone 4 Retina Display vs the human eye". April 30, 2013. Retrieved April 30, 2013. 
  16. ^ "Apple Retina Display". July 26, 2012. Retrieved July 26, 2012. 
  17. ^ a b Brownlee, John (June 15, 2012). "Why Retina Isn’t Enough". CultOfMac. Retrieved June 15, 2012. "There’s only one problem: Steve Jobs said that the human eye, viewing a display from 12 inches away, can’t discern individual pixels if the density is over 300 pixels per inch. Except that this “magic” number is wrong. The real number is closer to 900 pixels per inch. Apple’s Retina Displays are only about 33% of the way there... But while 20/20 vision might traditionally refer to “standard vision”, most research suggests that normal vision is actually much better than 20/20. In fact, people with normal vision usually won’t see their eyesight degrade to 20/20 until they are 60 or 70 years of age!... J. Blackwell of the Optical Society of America determined back in 1946 that the resolution of the human eye was actually closer to 0.35 arc minutes. Again, this means that for an iPhone 4S to have a true Retina Display, it would need pixels that were 65% smaller than it currently has... Such an argument is faulty. For one thing, no one sits a uniform average distance away from their devices. When you text on your iPhone, you might hold it at 12 inches, but if you’re squinting at it in the middle of the night to answer a phone call, you might hold it 6 inches away. And while you might write an email on your MacBook Pro at 24 inches, you might lean in on the edge of your seat during an exciting movie or game to closer to 18." 
  18. ^ "Visual Acuity". Precision Vision. "“Normal” visual acuity for healthy eyes is one or two lines better than 20/20. In population samples the average acuity does not drop to the 20/20 level until age 60 or 70. Always remember that the 20/20 reference standard does not refer to the average acuity of American eyes, just as the US standard foot is defined independently of the “normal” length of American feet."