Retina Display

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.

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. This allows displays to rival the smooth curves and sharpness of printed text and immediacy of photographic prints.

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. 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".

MacBook Pro

The MacBook Pro (sometimes abbreviated MBP) is a line of Macintosh portable computers introduced in January 2006 by Apple Inc., now in its third generation. Replacing the PowerBook G4, the MacBook Pro was the second model to be announced in the Apple–Intel transition, after the iMac. It is the high-end model of the MacBook family and is currently produced with 13- and 15-inch screens. A 17-inch version was available for sale in April 2006.

The first generation MacBook Pro appeared externally similar to the PowerBook G4, but used the Intel Core processors instead of PowerPC G4 chips. The 15-inch model was introduced first, in January 2006; the 17-inch model followed in April. Both received several updates and Core 2 Duo processors later that year.

The computer's second generation, known as the "unibody" model, has a more tapered design and a casing made from a single block of aluminum. It debuted in October 2008 as the 15-inch MacBook Pro and the 13-inch aluminum unibody MacBook. The following January brought the design to the 17-inch model, along with the built-in battery that joined the rest of the MacBook Pro line in June, during which Apple also absorbed the unibody 13" Macbook into the MacBook Pro line. Subsequent updates brought upgraded Intel Core i5 and i7 processors and introduced Intel's Thunderbolt technology.

Retina

The retina (UK /ˈrɛtɪnə/ RET-i-nə, US /ˈrɛtᵊnə/ RET-(ə-)nə, pl. retinae, /ˈrɛtiniː/; from Latin rēte, meaning "net") is the third and inner coat of the eye which is a light-sensitive layer of tissue. The optics of the eye create an image of the visual world on the retina (through the cornea and lens), which serves much the same function as the film in a camera. Light striking the retina initiates a cascade of chemical and electrical events that ultimately trigger nerve impulses. These are sent to various visual centres of the brain through the fibres of the optic nerve.

In vertebrate embryonic development, the retina and the optic nerve originate as outgrowths of the developing brain, so the retina is considered part of the central nervous system (CNS) and is actually brain tissue. It is the only part of the CNS that can be visualized non-invasively.

The retina is a layered structure with several layers of neurons interconnected by synapses. The only neurons that are directly sensitive to light are the photoreceptor cells. These are mainly of two types: the rods and cones. Rods function mainly in dim light and provide black-and-white vision, while cones support daytime vision and the perception of colour. A third, much rarer type of photoreceptor, the intrinsically photosensitive ganglion cell, is important for reflexive responses to bright daylight.