History of Apple Inc.
Apple Inc. Apple Computer, Inc. is a multinational corporation that creates consumer electronics, personal computers and computer software, is a digital distributor of media content. The company has a chain of retail stores known as Apple Stores. Apple's core product lines are the iPhone smartphone, iPad tablet computer, iPod portable media players, Macintosh computer line. Founders Steve Jobs and Steve Wozniak created Apple Computer on April 1, 1976, incorporated the company on January 3, 1977, in Cupertino, California. For more than three decades, Apple Computer was predominantly a manufacturer of personal computers, including the Apple II, Power Mac lines, but it faced rocky sales and low market share during the 1990s. Jobs, ousted from the company in 1985, returned to Apple in 1996 after his company NeXT was bought by Apple; the following year he became the company's interim CEO, which became permanent. Jobs subsequently instilled a new corporate philosophy of recognizable products and simple design, starting with the original iMac in 1998.
With the introduction of the successful iPod music player in 2001 and iTunes Music Store in 2003, Apple established itself as a leader in the consumer electronics and media sales industries, leading it to drop "Computer" from the company's name in 2007. The company is now known for its iOS range of smart phone, media player, tablet computer products that began with the iPhone, followed by the iPod Touch and iPad; as of 30 June 2015, Apple was the largest publicly traded corporation in the world by market capitalization, with an estimated value of US$1 trillion as of August 2, 2018. Apple's worldwide annual revenue in 2010 totaled US$65 billion, growing to US$127.8 billion in 2011 and $156 billion in 2012. Steve Jobs and Steve Wozniak had withdrawn from Reed College and UC Berkeley by 1975. Wozniak designed a video terminal. Alex Kamradt sold a small number of them through his firm. Aside from their interest in up-to-date technology, the impetus for Jobs and Wozniak referred to collectively as "the two Steves", seems to have had another source.
In his essay From Satori to Silicon Valley, cultural historian Theodore Roszak made the point that the Apple Computer emerged from within the West Coast counterculture and the need to produce print-outs, letter labels, databases. Roszak offers a bit of background on the development of the two Steves' prototype models. In 1975, Wozniak started attending meetings of the Homebrew Computer Club. New microcomputers such as the Altair 8800 and the IMSAI inspired him to build a microprocessor into his video terminal and have a complete computer. At the time the only microcomputer CPUs available were the $179 Intel 8080, the $170 Motorola 6800. Wozniak preferred the 6800. So he watched, learned, designed computers on paper, waiting for the day he could afford a CPU; when MOS Technology released its $20 6502 chip in 1976, Wozniak wrote a version of BASIC for it began to design a computer for it to run on. The 6502 was designed by the same people who designed the 6800, as many in Silicon Valley left employers to form their own companies.
Wozniak's earlier 6800 paper-computer needed only minor changes to run on the new chip. Wozniak took it to Homebrew Computer Club meetings to show it off. At the meeting, Wozniak met his old friend Jobs, interested in the commercial potential of the small hobby machines; the two Steves had been friends for some time, having met in 1971, when their mutual friend, Bill Fernandez, introduced 21-year-old Wozniak to 16-year-old Jobs. They began their partnership when Wozniak, a talented, self-educated electronics engineer, began constructing boxes which enabled one to make long-distance phone calls at no cost, sold several hundred models. Jobs managed to interest Wozniak in assembling a computer machine and selling it. Jobs approached a local computer store, The Byte Shop, who said they would be interested in the machine, but only if it came assembled; the owner, Paul Terrell, went further, saying he would order 50 of the machines and pay US $500 each on delivery. Jobs took the purchase order that he had been given from the Byte Shop to Cramer Electronics, a national electronic parts distributor, ordered the components he needed to assemble the Apple I Computer.
The local credit manager asked Jobs how he was going to pay for the parts and he replied, "I have this purchase order from the Byte Shop chain of computer stores for 50 of my computers and the payment terms are COD. If you give me the parts on a net 30-day terms I can build and deliver the computers in that time frame, collect my money from Terrell at the Byte Shop and pay you."The credit manager called Paul Terrell, attending an IEEE computer conference at Asilomar in Pacific Grove, verified the validity of the purchase order. Amazed at the tenacity of Jobs, Terrell assured the credit manager if the computers showed up in his stores, Jobs would be paid and would have more than enough money to pay for the parts order; the two Steves and their small crew spent day and night building and testing the computers, delivered to Terrell on time to pay his suppliers and have a tidy profit left over for their celebration and next order. Steve Jobs had found a way to finance his soon-to-be multimillion-dollar company without giving away one share of stock or ownership.
The machine had only a few notable features. One was the use of a TV as the display system, whereas
Subpixel rendering is a way to increase the apparent resolution of a computer's liquid crystal display or organic light-emitting diode display by rendering pixels to take into account the screen type's physical properties. It takes advantage of the fact that each pixel on a color LCD is composed of individual red and blue or other color subpixels to anti-alias text with greater detail or to increase the resolution of all image types on layouts which are designed to be compatible with subpixel rendering. A single pixel on a color subpixelated display is made of several color primaries three colored elements—ordered either as blue and red, or as red and blue; some displays have more than three primaries called MultiPrimary, such as the combination of red, green and yellow, or red, green and white, or red, blue and cyan. These pixel components, sometimes called subpixels, appear as a single color to the human eye because of blurring by the optics and spatial integration by nerve cells in the eye.
The components are visible, when viewed with a small magnifying glass, such as a loupe. Over a certain resolution threshold the colors in the subpixels are not visible, but the relative intensity of the components shifts the apparent position or orientation of a line. Subpixel rendering is better suited to some display technologies than others; the technology is well-suited to LCDs and other technologies where each logical pixel corresponds directly to three or more independent colored subpixels, but less so for CRTs. In a CRT the light from the pixel components spreads across pixels, the outputs of adjacent pixels are not independent. If a designer knew about the display's electron beams and aperture grille, subpixel rendering might have some advantage, but the properties of the CRT components, coupled with the alignment variations that are part of the production process, make subpixel rendering less effective for these displays. The technique should have good application to organic light emitting diodes and other display technologies that organize pixels the same way as LCDs.
The origin of subpixel rendering as used today remains controversial. Apple IBM, Microsoft patented various implementations with certain technical differences owing to the different purposes their technologies were intended for. Microsoft has several patents in the United States on subpixel rendering technology for text rendering on RGB Stripe layouts; the patents 6,219,025, 6,239,783, 6,307,566, 6,225,973, 6,243,070, 6,393,145, 6,421,054, 6,282,327, 6,624,828 were filed between 1998-10-07 and 1999-10-07, thus should expire in 2019-10-07. This caused FreeType, the library used by most current software on the X Window System, to disable this functionality by default. Most modern Linux distributions turn this back on. Apple was able to use it in Mac OS X due to a patent cross-licensing agreement, it is sometimes claimed that the Apple II, introduced in 1977, supports an early form of subpixel rendering in its high-resolution graphics mode. However, the method Gibson describes can be viewed as a limitation of the way the machine generates color, rather than as a technique intentionally exploited by programmers to increase resolution.
David Turner of the FreeType project criticized Gibson's theory as to the invention, at least as far as patent law is concerned, in the following way: "For the record, the Wozniak patent is explicitely referenced in the, the claims are worded to avoid colliding with it." Turner further explains his view: Under the current US regime, any minor improvement to a previous technique can be considered an "invention" and "protected" by a patent under the right circumstances, If we look at, we see that the Apple II Wozniak patent covering this machine's display technique is listed first in the patents' citations. This shows that both Microsoft and the patent examiner who granted the patents were aware of this "prior art"; the bytes that comprise the Apple II high-resolution screen buffer contain seven visible bits and a flag bit used to select between purple/green or blue/orange color sets. Each pixel, since it is represented by a single bit, is either off. Color is instead created as an artifact of the NTSC color encoding scheme, determined by horizontal position: pixels with horizontal coordinates are always purple, odd pixels are always green.
Two lit pixels next to each other are always white, regardless of whether the pair is even/odd or odd/even, irrespective of the value of the flag bit. The foregoing is only an approximation of the true interplay of the digital and analog behavior of the Apple's video output circuits on one hand, the properties of real NTSC monitors on the other hand. However, this approximation is what most programmers of the time would have in mind while working with the Apple's high-resolution mode. Gibson's example claims that because two adjacent bits make a white block, there are in fact two bits per pixel: one which activates the purple left half of the pixel, the other which activates the green right half of the pixel. If the programmer instead activates the green right half of a pixel and the purple half of the next pixel the result is a w
The iPod Nano is a portable media player designed and marketed by Apple Inc. The first generation model was introduced on September 7, 2005, as a replacement for the iPod Mini, using flash memory for storage; the iPod Nano went since its introduction. Apple discontinued the iPod Nano on July 27, 2017. Development work on the design of the iPod Nano started only nine months before its launch date; the Nano was launched in two colors with two available sizes: 2 GB and 4 GB. On February 7, 2006, Apple updated the lineup with the 1 GB model. Apple released some accessories, including armbands and silicone "tubes" designed to bring color to the Nano and protect it from scratches, as well as a combination lanyard-earphone accessory that hangs around the neck and avoids the problem of tangled earphone cords; the current models with Bluetooth headphones have a similar advantage. On September 7, 2005, Apple introduced the iPod Nano at a media event with Steve Jobs pointing to the small watch pocket in his jeans and asking, "Ever wonder what this pocket is for?"
Advertising emphasized the iPod Nano's small size: 40 millimetres wide, 90 millimetres long, 6.9 millimetres thick and weighing 42 grams. The stated battery life was up to 14 hours, while the screen was 176×132 pixels, 38 millimetres diagonal, displaying 65,536 colors. 1, 2, 4 GB capacities were available. On November 11, 2011, Apple announced a recall on this model of iPod nano; the recall was issued due to a battery overheat issue. This recall applied to iPod nanos sold between September 2005 and December 2006. On September 25, 2006, Apple updated the Nano line; the second-generation Nano featured scratch-resistant, anodized aluminum casing like the earlier Mini's design. However, unlike the second-generation Mini, the button labels were grey instead of matching the Nano's casing; the second-generation Nano featured a 40% brighter, "more vibrant" display, a battery life upgrade, storage sizes doubled to 2, 4, 8 GB models. The second generation introduced gapless playback of audio files, along with a new search option.
The 2 GB model was available in silver only. The 4 GB was available in green, silver, or pink, the 8 GB model was only available in black - red was added for 4 and 8 GB models. Apple claimed that the second generation iPod Nano's packaging was "32% lighter with 52% less volume than the first generation", thereby reducing environmental impact and shipping costs. On October 13, 2006, Apple announced a special edition iPod Nano. For each red iPod Nano sold in the United States, Apple donates US$10 to the Product Red initiative, while retaining the regular price. On November 3, 2006, Apple introduced a red 8 GB model, due to "outstanding customer demand", again retaining the same price point of the equivalent black model. Apple updated the Nano again on September 5, 2007; the third-generation Nano featured a 2-inch QVGA screen and a shorter, heavier design, with new colors. New features included browsing via Cover Flow, a new user interface, video playback, support for new iPod Games. Users had to repurchase games bought a month before the debut of the new iPod as they were not supported.
The Nano was announced in a 4 GB version coming in silver and an 8 GB version coming in silver, mint green and Product Red. The battery lasted for approx. 24 hours on audio playback and approx. 5 hours on video playback. On January 22, 2008, Apple released a pink version of the 8 GB iPod Nano. Combining elements from previous generations of the iPod Nano, the third-generation Nano had an aluminum front plate and a stainless steel back plate; the Nano sported a new Minimalistic hold switch, similar to the iPod Shuffle's power switch, moved to the bottom of the player. The 2-inch screen had the smallest dot pitch of any Apple product, having the same pixel count as the 2.5-inch display of the iPod Classic. On October 6, 2007, Apple released a firmware update via iTunes, said to improve Cover Flow and yield faster menu navigation; the update was released for the iPod Classic. On November 28, 2007, Apple released another firmware update via iTunes, which included unspecified bugfixes. January 15, 2008 saw the release of version 1.1, which added support for iTunes movie rentals, music song lyrics support and included more unspecified bugfixes.
Apple released update version 1.1.2 in May 2008 and version 1.1.3 in July 2008 with more bug fixes. At the Apple Let's Rock Event on September 9, 2008, the iPod Nano Fourth Generation was announced, it returned to the narrow form factor of the 1st and 2nd Generation model, while retaining and rotating the 51-millimetre screen from the 3rd gen model. It was thinner than the first and third generation Nano, measuring 90.7 millimetres tall by 38.7 millimetres wide by 6.2 millimetres thick, weighing 36.8 grams. It had a curved aluminum glass screen. Apple claimed the battery would last 24 hours of music playback, only 4 hours of video playback, compared to the 5 hours of the previous generation; the six previous colors were replaced by silver, purple, light blue, yellow, orange and pink, for a total of n
The Mac mini is a desktop computer made by Apple Inc. One of four desktop computers in the current Macintosh lineup, along with the iMac, Mac Pro, iMac Pro, it uses many components featured in laptops to achieve its small size; the current Mac mini, introduced in October 2018, is the fourth generation of the product. First released in 2005, the Mac mini is Apple's only consumer desktop computer since 1998 to ship without a display, keyboard, or mouse. Apple marketed it as BYODKM, pitching it to users switching from a traditional Windows PC. In 2010, a third-generation Mac mini became Apple's first computer with an HDMI video port to connect to a television or other display, more positioning the unit as a home theater device alternative to the Apple TV. A server version of the Mac mini, bundled with the Server edition of the OS X operating system, was offered from 2009 to 2014. A small form factor computer had been speculated and requested long before the release of the Mac mini. Rumors predicted that the "headless iMac" would be small, include no display, would be positioned as Apple's entry-level desktop computer.
On January 10, 2005, the Mac mini was announced alongside the iPod shuffle at the Macworld Conference & Expo and was described by Apple CEO Steve Jobs at the time as "the cheapest, most affordable Mac ever". Its case measured 2.0 × 6.5 × 6.5 inches. The Mac mini is an entry-level computer intended for budget-minded customers; until the 2011 release, the Mac mini had much less processing power than the other computers of the Macintosh lineup. Unlike regular desktop computers, which use standard-sized components such as 3.5-inch hard drives and full-size DIMM's, Apple uses lower-power laptop components in the Mac mini to fit all the necessary components into the small case and to prevent overheating. With the choice of components on the older models, the machine was considered somewhat slower than standard desktop computers, it had less storage and memory than comparable desktops. However, the 2011 upgrade addressed many of these previous complaints. In general, the Mac mini has been praised as a affordable computer with a solid range of features.
However, many agree that it is costly for a computer aimed at the lower segment of the market. It is possible to buy small computers at the same price with faster processors, better graphics card, more memory, more storage; the small size has made the Mac mini popular as a home theater solution. In addition, its size and reliability has helped keep resale values high. On October 22, 2009, Apple introduced a new server version of the Mac mini along with revisions of the computer; this model had a second hard drive instead of an optical drive, was marketed as an affordable server for small businesses and schools. On June 15, 2010, Apple introduced the third-generation Mac mini; the new model was thinner, with a unibody aluminum case designed to be opened for RAM access, incorporated upgraded hardware, such as an HDMI port and Nvidia GeForce 320M graphics. It included an internal power supply. An update announced July 20, 2011, dropped the internal CD/DVD optical drive from all versions and introduced a Thunderbolt port, Intel Core i5 processor, either Intel HD Graphics 3000 integrated graphics or AMD Radeon HD 6630M dedicated graphics.
The Server model was upgraded to a quad-core Intel Core i7 processor. Quad-core i7 CPUs were used in the late-2012 desktop Mac mini computers. In October 2014, Apple refreshed the line, adding Haswell CPUs, improving the graphics, lowering the base-model price by $100; the only change to the body was the removal of the two holes used to open the case, as the RAM was no longer upgradable because it was soldered to the logic board. On October 30, 2018, after four years, the Mac mini got a refresh. With this came major specification upgrades, new colors, a switch to all-flash storage; the RAM was increased to a baseline of 8 GB, a maximum of 64 GB of SO-DIMM DDR4. This shows Apple's trend back toward user-upgrade-ability in their desktop models; the storage was changed to a baseline 128 GB of flash storage, with a max of 2 TB. It has optional 10 Gb Ethernet, HDMI 2.0, a headphone jack, 2 USB 3.1, 4 USB-C Thunderbolt 3 ports. The Bluetooth was upgraded to the 5.0 standard, the Mac itself was made available in space gray.
The baseline retail price is $799 USD. Missing for the 2018 model is the SD card reader, SATA drive bay, IR receiver, optical S/PDIF audio out, audio in; the most notable feature of the Mac mini is its size. The original design measured only 2.0 × 6.5 × 6.5 inches. The exterior of the original Mac mini was made of aluminum capped with polycarbonate plastic on the top and bottom; the original design was not meant to be upgraded by the user. The back of the machine contains the I/O vents for the cooling system, it had an external power supply rated at 85W or 110W. The Mac mini, updated on June 15, 2010, was redesigned, being slimmer than the prior models at only 1.4 inches tall, but wider at 7.7 inches a side. The weight rose from 2.9 to 3.0 pounds. The power supply is now internal as opposed to external; the chassis no longer has the polycarbonate plastic on the bottom. The newer model, introduced July 20, 2011 has the same physical dimensions
MacOS is a series of graphical operating systems developed and marketed by Apple Inc. since 2001. It is the primary operating system for Apple's Mac family of computers. Within the market of desktop and home computers, by web usage, it is the second most used desktop OS, after Microsoft Windows.macOS is the second major series of Macintosh operating systems. The first is colloquially called the "classic" Mac OS, introduced in 1984, the final release of, Mac OS 9 in 1999; the first desktop version, Mac OS X 10.0, was released in March 2001, with its first update, 10.1, arriving that year. After this, Apple began naming its releases after big cats, which lasted until OS X 10.8 Mountain Lion. Since OS X 10.9 Mavericks, releases have been named after locations in California. Apple shortened the name to "OS X" in 2012 and changed it to "macOS" in 2016, adopting the nomenclature that they were using for their other operating systems, iOS, watchOS, tvOS; the latest version is macOS Mojave, publicly released in September 2018.
Between 1999 and 2009, Apple sold. The initial version, Mac OS X Server 1.0, was released in 1999 with a user interface similar to Mac OS 8.5. After this, new versions were introduced concurrently with the desktop version of Mac OS X. Beginning with Mac OS X 10.7 Lion, the server functions were made available as a separate package on the Mac App Store.macOS is based on technologies developed between 1985 and 1997 at NeXT, a company that Apple co-founder Steve Jobs created after leaving the company. The "X" in Mac OS X and OS X is pronounced as such; the X was a prominent part of the operating system's brand identity and marketing in its early years, but receded in prominence since the release of Snow Leopard in 2009. UNIX 03 certification was achieved for the Intel version of Mac OS X 10.5 Leopard and all releases from Mac OS X 10.6 Snow Leopard up to the current version have UNIX 03 certification. MacOS shares its Unix-based core, named Darwin, many of its frameworks with iOS, tvOS and watchOS.
A modified version of Mac OS X 10.4 Tiger was used for the first-generation Apple TV. Releases of Mac OS X from 1999 to 2005 ran on the PowerPC-based Macs of that period. After Apple announced that they were switching to Intel CPUs from 2006 onwards, versions were released for 32-bit and 64-bit Intel-based Macs. Versions from Mac OS X 10.7 Lion run on 64-bit Intel CPUs, in contrast to the ARM architecture used on iOS and watchOS devices, do not support PowerPC applications. The heritage of what would become macOS had originated at NeXT, a company founded by Steve Jobs following his departure from Apple in 1985. There, the Unix-like NeXTSTEP operating system was developed, launched in 1989; the kernel of NeXTSTEP is based upon the Mach kernel, developed at Carnegie Mellon University, with additional kernel layers and low-level user space code derived from parts of BSD. Its graphical user interface was built on top of an object-oriented GUI toolkit using the Objective-C programming language. Throughout the early 1990s, Apple had tried to create a "next-generation" OS to succeed its classic Mac OS through the Taligent and Gershwin projects, but all of them were abandoned.
This led Apple to purchase NeXT in 1996, allowing NeXTSTEP called OPENSTEP, to serve as the basis for Apple's next generation operating system. This purchase led to Steve Jobs returning to Apple as an interim, the permanent CEO, shepherding the transformation of the programmer-friendly OPENSTEP into a system that would be adopted by Apple's primary market of home users and creative professionals; the project was first code named "Rhapsody" and officially named Mac OS X. Mac OS X was presented as the tenth major version of Apple's operating system for Macintosh computers. Previous Macintosh operating systems were named using Arabic numerals, as with Mac OS 8 and Mac OS 9; the letter "X" in Mac OS X's name refers to a Roman numeral. It is therefore pronounced "ten" in this context. However, it is commonly pronounced like the letter "X"; the first version of Mac OS X, Mac OS X Server 1.0, was a transitional product, featuring an interface resembling the classic Mac OS, though it was not compatible with software designed for the older system.
Consumer releases of Mac OS X included more backward compatibility. Mac OS applications could be rewritten to run natively via the Carbon API; the consumer version of Mac OS X was launched in 2001 with Mac OS X 10.0. Reviews were variable, with extensive praise for its sophisticated, glossy Aqua interface but criticizing it for sluggish performance. With Apple's popularity at a low, the makers of several classic Mac applications such as FrameMaker and PageMaker declined to develop new versions of their software for Mac OS X. Ars Technica columnist John Siracusa, who reviewed every major OS X release up to 10.10, described the early releases in retrospect as'dog-slow, feature poor' and Aqua as'unbearably slow and a huge resource hog'. Apple developed several new releases of Mac OS X. Siracusa's review of version 10.3, noted "It's strange to have gone from years of uncertainty and vaporware to a steady annual supply of major new operating system releases." Version 10.4, Tiger shocked executives at Microsoft by offering a number of features, such as fast file s
Compositing is the combining of visual elements from separate sources into single images to create the illusion that all those elements are parts of the same scene. Live-action shooting for compositing is variously called "chroma key", "blue screen", "green screen" and other names. Today, though not all, compositing is achieved through digital image manipulation. Pre-digital compositing techniques, however, go back as far as the trick films of Georges Méliès in the late 19th century, some are still in use. All compositing involves the replacement of selected parts of an image with other material but not always, from another image. In the digital method of compositing, software commands designate a narrowly defined color as the part of an image to be replaced; the software replaces every pixel within the designated color range with a pixel from another image, aligned to appear as part of the original. For example, one could record a television weather presenter positioned in front of a plain blue or green background, while compositing software replaces only the designated blue or green color with weather maps.
In television studios, blue or green screens may back news-readers to allow the compositing of stories behind them, before being switched to full-screen display. In other cases, presenters may be within compositing backgrounds that are replaced with entire "virtual sets" executed in computer graphics programs. In sophisticated installations, cameras, or both can move about while the computer-generated imagery environment changes in real time to maintain correct relationships between the camera angles and virtual "backgrounds". Virtual sets are used in motion picture filmmaking photographed in blue or green screen environments, as for example in Sky Captain and the World of Tomorrow. More composited backgrounds are combined with sets – both full-size and models – and vehicles and other physical objects that enhance the realism of the composited visuals. "Sets" of unlimited size can be created digitally because compositing software can take the blue or green color at the edges of a backing screen and extend it to fill the rest of the frame outside it.
That way, subjects recorded in modest areas can be placed in large virtual vistas. Most common are set extensions: digital additions to actual performing environments. In the film Gladiator, for example, the arena and first tier seats of the Roman Colosseum were built, while the upper galleries were computer graphics, composited onto the image above the physical set. For motion pictures recorded on film, high-quality video conversions called "digital intermediates" enable compositing and other operations of computerized post production. Digital compositing is a type of matting, one of four basic compositing methods; the others are physical compositing, multiple exposure, background projection, a method which utilizes both front projection and rear projection. In physical compositing the separate parts of the image are placed together in the photographic frame and recorded in a single exposure; the components are aligned. The most common physical compositing elements are partial models and glass paintings.
Partial models are used as set extensions such as ceilings or the upper stories of buildings. The model, built to match the actual set but on a much smaller scale, is hung in front of the camera, aligned so that it appears to be part of the set. Models are quite large because they must be placed far enough from the camera so that both they and the set far beyond them are in sharp focus. Glass shots are made by positioning a large pane of glass so that it fills the camera frame, is far enough away to be held in focus along with the background visible through it; the entire scene is painted on the glass, except for the area revealing the background where action is to take place. This area is left clear. Photographed through the glass, the live action is composited with the painted area. A classic example of a glass shot is the approach to Ashley Wilkes' plantation in Gone with the Wind; the plantation and fields are all painted, while the road and the moving figures on it are photographed through the glass area left clear.
A variant uses the opposite technique: most of the area is clear, except for individual elements affixed to the glass. For example, a ranch house could be added to an empty valley by placing an appropriately scaled and positioned picture of it between the valley and the camera. An in-camera multiple exposure is made by recording on only one part of each film frame, rewinding the film to the same start point, exposing a second part, repeating the process as needed; the resulting negative is a composite of all the individual exposures. Exposing one section at a time is made possible by enclosing the camera lens in a light-tight box fitted with maskable openings, each one corresponding to one of the action areas. Only one opening is revealed per exposure. Multiple exposure is difficult. However, as early as 1900 Georges Méliès used seven-fold exposure in L'homme-orchestre/The One-man Band.
In digital signal processing, spatial anti-aliasing is a technique for minimizing the distortion artifacts known as aliasing when representing a high-resolution image at a lower resolution. Anti-aliasing is used in digital photography, computer graphics, digital audio, many other applications. Anti-aliasing means removing signal components that have a higher frequency than is able to be properly resolved by the recording device; this removal is done before sampling at a lower resolution. When sampling is performed without removing this part of the signal, it causes undesirable artifacts such as the black-and-white noise near the top of figure 1-a below. In signal acquisition and audio, anti-aliasing is done using an analogue anti-aliasing filter to remove the out-of-band component of the input signal prior to sampling with an analogue-to-digital converter. In digital photography, optical anti-aliasing filters made of birefringent materials smooth the signal in the spatial optical domain; the anti-aliasing filter blurs the image in order to reduce the resolution to or below that achievable by the digital sensor.
In computer graphics, anti-aliasing improves the appearance of polygon edges, so they are not "jagged" but are smoothed out on the screen. However, it uses more video memory; the level of anti-aliasing determines. Figure 1-a illustrates the visual distortion. Near the top of the image, where the checker-board is small, the image is both difficult to recognise and not aesthetically appealing. In contrast, Figure 1-b shows an anti-aliased version of the scene; the checker-board near the top blends into grey, the desired effect when the resolution is insufficient to show the detail. Near the bottom of the image, the edges appear much smoother in the anti-aliased image. Figure 1-c shows another anti-aliasing algorithm, based on the sinc filter, considered better than the algorithm used in 1-b. Figure 2 shows magnified portions of Figure 1-c for comparison. In Figure 1-c, anti-aliasing has interpolated the brightness of the pixels at the boundaries to produce grey pixels since the space is occupied by both black and white tiles.
These help make. In Figure 3, anti-aliasing was used to blend the boundary pixels of a sample graphic. Anti-aliasing is applied in rendering text on a computer screen, to suggest smooth contours that better emulate the appearance of text produced by conventional ink-and-paper printing. With fonts displayed on typical LCD screens, it is common to use subpixel rendering techniques like ClearType. Sub-pixel rendering requires special colour-balanced anti-aliasing filters to turn what would be severe colour distortion into barely-noticeable colour fringes. Equivalent results can be had by making individual sub-pixels addressable as if they were full pixels, supplying a hardware-based anti-aliasing filter as is done in the OLPC XO-1 laptop's display controller. Pixel geometry affects all of this, whether the anti-aliasing and sub-pixel addressing are done in software or hardware; the most basic approach to anti-aliasing a pixel is determining what percentage of the pixel is occupied by a given region in the vector graphic - in this case a pixel-sized square transposed over several pixels - and using that percentage as the colour.
A basic plot of a single, white-on-black anti-aliased point using that method can be done as follows: Define function PlotAntiAliasedPoint For roundedx = floor to ceil do For roundedy = floor to ceil do percent_x = 1 - abs percent_y = 1 - abs percent = percent_x * percent_y DrawPixel This method is best suited for simple graphics, such as basic lines or curves, applications that would otherwise have to convert absolute coordinates to pixel-constrained coordinates, such as 3-D graphics. It is a fast function, but it is low-quality, gets slower as the complexity of the shape increases. For purposes requiring high-quality graphics or complex vector shapes, this will not be the best approach. Note: The DrawPixel routine above cannot blindly set the colour value to the percent calculated, it must add the new value to the existing value at that location up to a maximum of 1. Otherwise, the brightness of each pixel will be equal to the darkest value calculated in time for that location which produces a bad result.
For example, if one point sets a brightness level of 0.90 for a given pixel and another point calculated barely touches that pixel and has a brightness of 0.05, the final value set for that pixel should be 0.95, not 0.05. For more sophisticated shapes, the algorithm may be generalized as rendering the shape to a pixel grid with higher resolution than the target display surface using bicubic interpolation to determine the average intensity of each real pixel on the display surface. In this approach, the ideal image is regarded as a signal; the image displayed on the screen is taken as samples, at each pixel position, of a filtered version of the