Retina display: Difference between revisions
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* ''For comparisons, see also: [[List of displays by pixel density]]'' |
* ''For comparisons, see also: [[List of displays by pixel density]]'' |
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=== Trigonometrical pixel density of Retina Display === |
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| ⚫ | Another unit of measurement for displays is [[pixels per degree]] (PPD), which measures the pixel density in relation to the user's viewing angle. When introducing the iPhone 4, Steve Jobs said the magic number for a retina display is about 300 PPI for a device held 10 to 12 inches from the eye<ref>[http://m.npr.org/story/127530049 NPR Live Blog of iPhone 4 Introduction]</ref>, which is 53 PPD at 10 inches. If a display's pixel density is more than 53 PPD (57 PPD for the iPhone 4 display){{cn|date=December 2012}} viewed from its optimal distance, that is a Retina Display.<!-- FALSE. Apple does not define Retina Display by a specific value of PPD. They define a display as Retina Display whenever their marketing team feel like it.--> 53 PPD pixel density means that there are 53 pixels visible in one degree view angle. For example, 53 PPD means that when viewed from the expected distance, if an imaginary triangle is drawn between two chosen pixels and the eye of the viewer, with a one-degree angle formed at the vertex of the triangle that is at the viewer's eye, then there will be 53 pixels along the opposite side of the triangle (between the other two vertices of the triangle, which are at the chosen 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 x 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 multiplying the distance to the screen times the PPI resolution of the screen times [[Pi|{{pi}}]] divided by 180 degrees. |
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== Criticism == |
== Criticism == |
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Revision as of 17:15, 2 December 2012
Retina Display is a brand name used by Apple for liquid crystal displays which they claim 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.[1] 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 while the Macbook Pro displays are mostly made by LG's suppliers,[2] along with the iPhone and iPod Touch displays.[citation needed] 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.
Technical information
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Apple markets the following devices as having retina displays.
| Model | PPI (pixels per inch) | ppcm (pixels per cm) | Resolution | Typical Viewing Distance (in/cm) | Pixels per Degree (PPD) |
|---|---|---|---|---|---|
| iPhone 4/4S and iPod Touch (4th generation) | 326 | 128 | 960×640 | 10 inches (25 cm) | 57 |
| iPhone 5 and iPod Touch (5th generation) | 1136×640 | ||||
| iPad (3rd/4th generation) | 264 | 105 | 2048×1536 | 15 inches (38 cm) | 69 |
| MacBook Pro with Retina Display 15" | 220 | 87 | 2880×1800 | 20 inches (51 cm) | 77 |
| MacBook Pro with Retina Display 13" | 227 | 89 | 2560×1600 | 20 inches (51 cm) | 79 |
- For comparisons, see also: List of displays by pixel density
Trigonometrical pixel density of Retina Display
Another unit of measurement for displays is pixels per degree (PPD), which measures the pixel density in relation to the user's viewing angle. When introducing the iPhone 4, Steve Jobs said the magic number for a retina display is about 300 PPI for a device held 10 to 12 inches from the eye[5], which is 53 PPD at 10 inches. If a display's pixel density is more than 53 PPD (57 PPD for the iPhone 4 display)[citation needed] viewed from its optimal distance, that is a Retina Display. 53 PPD pixel density means that there are 53 pixels visible in one degree view angle. For example, 53 PPD means that when viewed from the expected distance, if an imaginary triangle is drawn between two chosen pixels and the eye of the viewer, with a one-degree angle formed at the vertex of the triangle that is at the viewer's eye, then there will be 53 pixels along the opposite side of the triangle (between the other two vertices of the triangle, which are at the chosen 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 x 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 multiplying the distance to the screen times the PPI resolution of the screen times π divided by 180 degrees.
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.[6] 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."[7] 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."[8]
See also
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References
- ^ "Apple - Learn about the Retina Display". Retrieved 2010-06-21.
- ^ "iFixit Teardown". Retrieved 2012-07-09.
- ^ United States Patent and Trademark Office. "Latest Status Info - Serial Number 85056807". Trademark Applications and Registrations Retrieval. Retrieved 2012-06-19. Claims priority filing date with respect to prior application in Jamaica.
- ^ Canadian Intellectual Property Office. "Canadian Trade-Mark Data - Application Number 1483982". Canadian Trade-marks Database. Retrieved 2012-06-19. Also cites prior application in Jamaica.
- ^ NPR Live Blog of iPhone 4 Introduction
- ^ "Analyst Challenges Apple's iPhone 4 'Retina Display' Claims". Retrieved 2010-06-10.
- ^ "Resolving the iPhone resolution". Retrieved 2010-06-21.
- ^ "Apple Retina Display". Retrieved 2012-07-25.