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Composite Artifact Colors
Composite artifact colors is a technique commonly used to address several graphic modes of some 1970s and 1980s home computers. With some machines, when connected to an NTSC TV or monitor over composite video outputs, the video signal encoding allowed for extra colors to be displayed, by manipulating the pixel position on screen, not being limited by each machine's hardware color palette. This mode was used mainly for games, since it limits the display's effective horizontal resolution. It was most common on the IBM PC (with CGA graphics), TRS-80 Color Computer, Apple II and Atari 8-bit computers, and used by the ''Ultima (series), Ultima'' role-playing video games. Software titles (such as ''King's Quest'' for the IBM PC) usually provided an option to select between ''"RGB mode"'' and ''"Color Composite mode"''. On PAL displays the effect is also present, but generates more limited colors. Depending on the exact PAL system used results will vary (if PAL-M or PAL-N are use ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Amiga
Amiga is a family of personal computers produced by Commodore International, Commodore from 1985 until the company's bankruptcy in 1994, with production by others afterward. The original model is one of a number of mid-1980s computers with 16-bit or 16/32-bit processors, 256 KB or more of RAM, mouse-based GUIs, and significantly improved graphics and audio compared to previous 8-bit systems. These include the Atari ST as well as the Macintosh 128K, Macintosh and Acorn Archimedes. The Amiga differs from its contemporaries through custom hardware to accelerate graphics and sound, including sprite (computer graphics), sprites, a blitter, and four channels of sample-based audio. It runs a pre-emptive multitasking operating system called AmigaOS, with a desktop environment called Workbench (AmigaOS), Workbench. The Amiga 1000, based on the Motorola 68000 microprocessor, was released in July 1985. Production problems kept it from becoming widely available until early 1986. While ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ultima II
''Ultima II: The Revenge of the Enchantress'', released on August 24, 1982, for the Apple II (United States Copyright Office, USCO# PA-317-502), is the second role-playing video game in the ''Ultima (series), Ultima'' series, and the second installment in Ultima's "Age of Darkness" trilogy. It is also the only official ''Ultima'' game published by Sierra On-Line. Conflict with Sierra over royalties for the IBM port of this game led the series creator Richard Garriott to start his own company, Origin Systems. The plot of ''Ultima II'' revolves around the evil enchantress Minax, taking over the world and exacting revenge on the player for the player's defeat of Mondain in '' Ultima''. The player travels through time to acquire the means to defeat Minax and restore the world to peace. ''Ultima II'' has a larger game world than ''Ultima I'', and hosts advances in graphics and in gameplay. Gameplay The gameplay is very similar to the previous game in the series, '' Ultima I: T ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Demoscene
The demoscene () is an international computer art subculture focused on producing demos: self-contained, sometimes extremely small, computer programs that produce audiovisual presentations. The purpose of a demo is to show off computer programming, programming, visual art, and musical skills. Demos and other demoscene productions (graphics, music, videos, games) are shared, voted on and released online at festivals known as Demoscene#Parties, demoparties. The scene started with the home computer revolution of the early 1980s, and the subsequent advent of software cracking. Crackers altered the code of computer games to remove copy protection, claiming credit by adding introduction screens of their own ("crack intro, cracktros"). They soon started competing for the best visual presentation of these additions. Through the making of intros and stand-alone demos, a new community eventually evolved, independent of the gaming and Warez scene, software sharing scenes. Demos are informa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Composite Monitor
A composite monitor or composite video monitor is any analog video display that receives input in the form of an analog composite video signal to a defined specification. A composite video signal encodes all information on a single conductor; a composite cable has a single live conductor plus earth. Other equipment with display functionality includes monitors with more advanced interfaces and connectors giving a better picture, including analog VGA, and digital DVI, HDMI, and DisplayPort; and television (TV) receivers which are self-contained, receiving and displaying video RF broadcasts received with an internal tuner. Video monitors are used for displaying computer output, closed-circuit television (e.g. security cameras) and other applications requiring a two-dimensional monochrome or colour image. Inputs Composite monitors usually use RCA jacks or BNC connectors for video input. Earlier equipment (1970s) often used UHF connectors. Typically simple composite monito ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dithering
Dither is an intentionally applied form of noise used to randomize quantization error, preventing large-scale patterns such as color banding in images. Dither is routinely used in processing of both digital audio and video data, and is often one of the last stages of mastering audio to a CD. A common use of dither is converting a grayscale image to black and white, so that the density of black dots in the new image approximates the average gray level in the original. Etymology The term ''dither'' was published in books on analog computation and hydraulically controlled guns shortly after World War II. Though he did not use the term ''dither'', the concept of dithering to reduce quantization patterns was first applied by Lawrence G. Roberts in his 1961 MIT master's thesis and 1962 article. By 1964 dither was being used in the modern sense described in this article. The technique was in use at least as early as 1915, though not under the name ''dither''. In digital proce ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chrominance
Chrominance (''chroma'' or ''C'' for short) is the signal used in video systems to convey the color information of the picture (see YUV color model), separately from the accompanying Luma (video), luma signal (or Y' for short). Chrominance is usually represented as two color-difference components: U = B-Y, B′ − Y′ (blue − luma) and V = R-Y, R′ − Y′ (red − luma). Each of these different components may have scale factors and offsets applied to it, as specified by the applicable video standard. In composite video signals, the U and V signals modulate a color subcarrier signal, and the result is referred to as the chrominance signal; the Phase (waves), phase and amplitude of this modulated chrominance signal correspond approximately to the hue and Saturation (color theory), saturation of the color. In digital-video and still-image color spaces such as Y′CbCr, the luma and chrominance components are digita ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Luminance
Luminance is a photometric measure of the luminous intensity per unit area of light travelling in a given direction. It describes the amount of light that passes through, is emitted from, or is reflected from a particular area, and falls within a given solid angle. The procedure for conversion from spectral radiance to luminance is standardized by the CIE and ISO. Brightness is the term for the ''subjective'' impression of the ''objective'' luminance measurement standard (see for the importance of this contrast). The SI unit for luminance is candela per square metre (cd/m2). A non-SI term for the same unit is the nit. The unit in the Centimetre–gram–second system of units (CGS) (which predated the SI system) is the stilb, which is equal to one candela per square centimetre or 10 kcd/m2. Description Luminance is often used to characterize emission or reflection from flat, diffuse surfaces. Luminance levels indicate how much luminous power could be det ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bandwidth (signal Processing)
Bandwidth is the difference between the upper and lower Frequency, frequencies in a continuous Frequency band, band of frequencies. It is typically measured in unit of measurement, unit of hertz (symbol Hz). It may refer more specifically to two subcategories: ''Passband bandwidth'' is the difference between the upper and lower cutoff frequencies of, for example, a band-pass filter, a communication channel, or a signal spectrum. ''Baseband bandwidth'' is equal to the upper cutoff frequency of a low-pass filter or baseband signal, which includes a zero frequency. Bandwidth in hertz is a central concept in many fields, including electronics, information theory, digital communications, radio communications, signal processing, and spectroscopy and is one of the determinants of the capacity of a given communication channel. A key characteristic of bandwidth is that any band of a given width can carry the same amount of information, regardless of where that band is located in the f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Composite Video
Composite video, also known as CVBS (composite video baseband signal or color, video, blanking and sync), is an analog video format that combines image information—such as brightness (luminance), color (chrominance), and synchronization, into a single signal transmitted over one channel. It is most commonly used for standard-definition television, and is sometimes referred to as ''SD video''. The signal is typically carried on a yellow RCA connector, with separate connectors used for left and right audio channels. In professional equipment, a BNC connector is often used instead. Other connector types may appear in compact consumer devices like digital cameras. Composite video supports several line resolutions, including 405-line, 525-line, and 625-line interlaced formats. It exists in three major regional variants based on analog color encoding standards: NTSC, PAL, and SECAM. The same format can also be used to transmit monochrome (black-and-white) video. Signal comp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Analog Television
Analog television is the original television technology that uses analog signals to transmit video and audio. In an analog television broadcast, the brightness, colors and sound are represented by amplitude, instantaneous phase and frequency, phase and frequency of an analog signal. Analog signals vary over a continuous range of possible values which means that electronic noise and interference may be introduced. Thus with analog, a moderately weak signal becomes Noise (video), snowy and subject to interference. In contrast, picture quality from a digital television (DTV) signal remains good until the signal level drops below digital cliff, a threshold where reception is no longer possible or becomes intermittent. Analog television may be wireless (terrestrial television and satellite television) or can be distributed over a cable network as cable television. All broadcast television systems used analog signals before the arrival of DTV. Motivated by the lower bandwidth requ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Frequency Modulation
Frequency modulation (FM) is a signal modulation technique used in electronic communication, originally for transmitting messages with a radio wave. In frequency modulation a carrier wave is varied in its instantaneous frequency in proportion to a property, primarily the instantaneous amplitude, of a message signal, such as an audio signal. The technology is used in telecommunications, radio broadcasting, signal processing, and Run-length limited#FM: .280.2C1.29 RLL, computing. In Analog signal, analog frequency modulation, such as radio broadcasting of voice and music, the instantaneous frequency deviation, i.e. the difference between the frequency of the carrier and its center frequency, has a functional relation to the modulating signal amplitude. Digital data can be encoded and transmitted with a type of frequency modulation known as frequency-shift keying (FSK), in which the instantaneous frequency of the carrier is shifted among a set of frequencies. The frequencies m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
