Retina Display

This article is about the HD screens of Apple products. It is not to be confused with Virtual retinal display.
Retina Display on iPhone 4
Part of a Retina Display on an iPhone 4. The pixels are not visible at viewing distance, creating an impression of sharp print-like text.
Retina Display on iPhone 3GS
Part of a non-Retina Display on an iPhone 3GS. The pixels are visible at viewing distance.

Retina Display (marketed by Apple with a lowercase 'D' as Retina display) is a brand name used by Apple for screens that have a higher pixel density than their previous models.[1]

The goal of Retina Displays is to make the display of text and images extremely crisp, so pixels are not visible to the naked eye.[2] This allows displays to rival the smooth curves and sharpness of printed text and immediacy of photographic prints.[3][4][5]

These better quality displays have been gradually released over a number of years, and the term is now used for nearly all of Apple products containing a screen, including the Apple Watch, iPhone, iPod Touch, iPad, Macbook, MacBook Pro, and iMac.[6] Apple uses slightly different versions of the term for these models, including Retina HD Display (iPhone 6 models), and Retina 5K Display, Retina HD Display or Retina 4K/5K Display (iMac).

Apple's Retina Displays are not an absolute standard but vary depending on the size of the display on the device, and how close the user would typically be viewing the screen. Where users view the screen at a closer distance to their eyes, as on smaller devices with smaller displays, the displays have more PPI (Pixels Per Inch), whilst larger devices with larger displays where the user views the screen further away use fewer PPI. Later device versions have had additional improvement, either counted by an increase in the screen size (the iPhone 6 Plus) and/or by PPI (the iPhone 6 and 6 Plus, and iMac with Retina 4K/5K Display), thus Apple using the name "Retina HD Display" or "Retina 4K/5K Display".

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.[7][8] 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

The displays are manufactured worldwide by different suppliers. Currently, the iPad's display comes from Samsung,[9] while the MacBook Pro, iPhone, and iPod Touch displays are made by LG[10] and Japan Display Inc.[11] 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 4K/5K Display:

Model[12][13][14][15][16] Marketing name Screen size Resolution Pixel density Pixel size
(mm)		 Angular pixel density
(px/°; at typ. distance)		 Typical viewing
distance		 Total pixels
(ppi) (px/cm)
Apple Watch 38mm Retina Display 33.5 mm (1.32 in) 272×340 330 114 0.087 57.6 10 in
(25 cm)		 92,480
Apple Watch 42mm 39 mm (1.5 in) 312×390 333 119 0.083 58.2 121,680
iPhone 4, and 4S and iPod Touch (4th generation) 3.5-inch 960×640 326 128 0.078 57.9 614,400
iPhone 5, 5C, and 5S and iPod Touch (5th generation, 6th generation) 4-inch 1136×640 57.5 727,040
iPhone 6 and iPhone 6S Retina HD Display 4.7-inch 1334×750 57.6 1,000,500
iPhone 6 Plus and iPhone 6S Plus 5.5-inch 1920×1080 401 157 0.063 71.2 2,073,600
iPad Mini 2, 3, and 4 Retina Display 7.9-inch 2048×1536 326 128 0.078 86.1 15 in
(38 cm)		 3,145,728
iPad (3rd, 4th generation, Air, and Air 2) 9.7-inch 264 105 0.096 70.6
iPad Pro 12.9-inch 2732×2048 71.9 5,595,136
MacBook (2015) 12" 12-inch 2304×1440 226 89 0.11 80.7 20 in
(51 cm)		 3,317,760
MacBook Pro (3rd generation) 13" 13.3-inch 2560×1600 227 81.3 4,096,000
MacBook Pro (3rd generation) 15" 15.4-inch 2880×1800 220 87 0.12 79.6 5,184,000
iMac with Retina 4K Display 21.5" Retina 4K Display 21.5-inch 4096×2304 219 86 81.6 9,437,184
iMac with Retina 5K Display 27" Retina 5K Display 27-inch 5120×2880 218 84 14,745,600

Technical definition

When introducing the iPhone 4, Steve Jobs said the number 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' predicted number of 300, the threshold for a Retina Display starts at the PPD value of 57 PPD. 57 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 57 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. 1920×1080 pixels) or relative pixel density (e.g. 401 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.

Reception

Reviews of Apple devices with retina displays have generally been positive on technical grounds, with comments describing it as a considerable improvement on earlier screens and praising Apple for driving third-party application support for high-resolution displays more effectively than on Windows.[17][18][19] While high-dpi displays such as IBM's T220 and T221 had been sold in the past, they had seen little takeup due to their cost of around $8400.[20]

As is common with Apple, there was also criticism of Apple's higher prices and profit margins.[21] Reviewing the iPhone 4 in 2010, writer Joshua Topolsky commented:

"to our eyes, there has never been a more detailed, clear, or viewable screen on any mobile device. Not only are the colors and blacks deep and rich, but you simply cannot see pixels on the screen. Okay, if you take some macro camera shots or get right up in there you can make them out [but] webpages that would be line after line of pixelated content when zoomed out on a 3GS are completely readable on the iPhone 4, though the text is beyond microscopic."[22]

Former Microsoft employee Bill Hill, an expert on font rendering, offered similar comments:

That much resolution is stunning. To see it on a mainstream device like the iPad - rather than a $13,000 exotic monitor - is truly amazing, and something I've been waiting more than a decade to see. It will set a bar for future resolution that every other manufacturer of devices and PCs will have to jump.[23][24]

Writer John Gruber suggested that the arrival of retina displays on computers would trigger a need to redesign interfaces and designs for the new displays:

The sort of rich, data-dense information design espoused by Edward Tufte can now not only be made on the computer screen but also enjoyed on one. Regarding font choices, you not only need not choose a font optimized for rendering on screen, but should not. Fonts optimized for screen rendering look cheap on the retina MacBook Pro — sometimes downright cheesy — in the same way they do when printed in a glossy magazine.[25]

Criticism

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).[26] 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."[27] Shortly after Soneira's challenge, the Boys of Tech podcast published their own analysis[28] 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."[29]

Apple fan website CultOfMac stated that the resolution the human eye can discern at 12 inches is 900 PPI, concluding "Apple’s Retina Displays are only about 33% of the way there."[30] On the topic of 20/20 vision, they 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"[30] (confirmed by vision testing experts Precision Vision).[31] 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.[30]

See also

References

  1. 1 2 "NPR Live Blog of iPhone 4 Introduction". NPR. June 7, 2010. Retrieved June 4, 2014.
  2. ↑ Jobs, Steve. "Apple iPhone 4 announcement". YouTube. Apple. Retrieved 28 July 2015.
  3. ↑ Nielsen, Jakob. "Serif vs. Sans-Serif Fonts for HD Screens". Nielsen Norman Group. Retrieved 28 July 2015.
  4. ↑ "Apple iPad 3 press release". Apple. Retrieved 28 July 2015.
  5. ↑ Gruber, John. "Pixel Perfect". Daring Fireball. Retrieved 28 July 2015.
  6. ↑ "Apple – Learn about the Retina display". Retrieved June 21, 2010.
  7. ↑ 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.
  8. ↑ 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.
  9. ↑ "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.
  10. ↑ "iFixit Teardown". iFixit. Retrieved July 9, 2012.
  11. ↑ "News related to IPO of Japan Display Inc.". March 19, 2014. Retrieved March 20, 2014.
  12. ↑ "Apple – iPod Touch – Technical Specifications".
  13. ↑ "Apple – iPhone – Technical Specifications".
  14. ↑ "Apple – iPad – Technical Specifications".
  15. ↑ "Apple – MacBook Pro – Technical Specifications".
  16. ↑ "Apple – iMac – Technical Specifications".
  17. ↑ Castle, Alex. "How to make the Windows desktop look good on high-DPI displays". PC World. Retrieved 9 July 2015.
  18. ↑ Cunningham, Andrew. "Using the Retina MacBook as a Windows PC". Ars Technica. Retrieved 9 July 2015.
  19. ↑ Hutchinson, Lee. "The Retina iMac and its 5K display… as a gaming machine? [Updated]". Ars Technica. Retrieved 9 July 2015.
  20. ↑ Novakovic, Nebojsa. "IBM T221 - the world's finest monitor?". The Inquirer. Retrieved 30 August 2015.
  21. ↑ Orlowski, Andrew. "Apple's Retina Macs: A little too elite?". The Register. Retrieved 9 July 2015.
  22. ↑ Topolsky, Joshua. "iPhone 4 review". Engadget. Retrieved 9 July 2015.
  23. ↑ Hill, Bill. "The Future of Reading (quoted)". Blog (archived).
  24. ↑ Atwood, Jeff. "Welcome to the Post PC Era". Coding Horror. Retrieved 9 July 2015.
  25. ↑ Gruber, John. "Pixel Perfect". Daring Fireball. Retrieved 18 September 2015.
  26. ↑ "Analyst challenges Apple's iPhone 4S 'Retina Display' claims". June 9, 2010. Retrieved June 10, 2010.
  27. ↑ "Resolving the iPhone resolution". June 21, 2010. Retrieved June 21, 2010.
  28. ↑ "iPhone 4 Retina Display vs the human eye". April 30, 2013. Retrieved April 30, 2013.
  29. ↑ "Apple Retina Display". July 26, 2012. Retrieved July 26, 2012.
  30. 1 2 3 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.
  31. ↑ "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.
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