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A framebuffer (frame buffer, or sometimes framestore) is a portion of
random-access memory Random-access memory (RAM; ) is a form of computer memory that can be read and changed in any order, typically used to store working Data (computing), data and machine code. A Random access, random-access memory device allows data items to b ...
(RAM) containing a
bitmap In computing, a bitmap is a mapping from some domain (for example, a range of integers) to bits. It is also called a bit array A bit array (also known as bitmask, bit map, bit set, bit string, or bit vector) is an array data structure that c ...
that drives a video display. It is a
memory buffer In computer science, a data buffer (or just buffer) is a region of a memory used to temporarily store data while it is being moved from one place to another. Typically, the data is stored in a buffer as it is retrieved from an input device (such a ...
containing data representing all the
pixel In digital imaging, a pixel (abbreviated px), pel, or picture element is the smallest addressable element in a raster image, or the smallest point in an all points addressable display device. In most digital display devices, pixels are the smal ...
s in a complete
video frame In filmmaking, video production, animation, and related fields, a frame is one of the many '' still images'' which compose the complete '' moving picture''. The term is derived from the historical development of film stock, in which the sequenti ...
. Modern
video card A graphics card (also called a video card, display card, graphics adapter, VGA card/VGA, video adapter, display adapter, or mistakenly GPU) is an expansion card which generates a feed of output images to a display device, such as a computer moni ...
s contain framebuffer circuitry in their cores. This circuitry converts an in-memory bitmap into a
video signal Video is an electronic medium for the recording, copying, playback, broadcasting, and display of moving visual media. Video was first developed for mechanical television systems, which were quickly replaced by cathode-ray tube (CRT) systems ...
that can be displayed on a computer monitor. In
computing Computing is any goal-oriented activity requiring, benefiting from, or creating computing machinery. It includes the study and experimentation of algorithmic processes, and development of both hardware and software. Computing has scientific, e ...
, a screen buffer is a part of
computer memory In computing, memory is a device or system that is used to store information for immediate use in a computer or related computer hardware and digital electronic devices. The term ''memory'' is often synonymous with the term ''primary storage ...
used by a computer application for the representation of the content to be shown on the
computer display A computer monitor is an output device that displays information in pictorial or textual form. A discrete monitor comprises a visual display, support electronics, power supply, housing, electrical connectors, and external user controls. The d ...
. The screen buffer may also be called the video buffer, the regeneration buffer, or regen buffer for short. Screen buffers should be distinguished from
video memory Dynamic random-access memory (dynamic RAM or DRAM) is a type of random-access semiconductor memory that stores each bit of data in a memory cell, usually consisting of a tiny capacitor and a transistor, both typically based on metal-oxide ...
. To this end, the term off-screen buffer is also used. The information in the buffer typically consists of color values for every
pixel In digital imaging, a pixel (abbreviated px), pel, or picture element is the smallest addressable element in a raster image, or the smallest point in an all points addressable display device. In most digital display devices, pixels are the smal ...
to be shown on the display. Color values are commonly stored in 1-bit
binary Binary may refer to: Science and technology Mathematics * Binary number, a representation of numbers using only two digits (0 and 1) * Binary function, a function that takes two arguments * Binary operation, a mathematical operation that t ...
(monochrome), 4-bit palettized, 8-bit palettized, 16-bit
high color High color graphics is a method of storing image information in a computer's memory such that each pixel is represented by two bytes. Usually the color is represented by all 16 bits, but some devices also support 15-bit high color. More recently ...
and 24-bit true color formats. An additional
alpha channel In computer graphics, alpha compositing or alpha blending is the process of combining one image with a background to create the appearance of partial or full transparency. It is often useful to render picture elements (pixels) in separate pas ...
is sometimes used to retain information about pixel transparency. The total amount of memory required for the framebuffer depends on the
resolution Resolution(s) may refer to: Common meanings * Resolution (debate), the statement which is debated in policy debate * Resolution (law), a written motion adopted by a deliberative body * New Year's resolution, a commitment that an individual mak ...
of the output signal, and on the
color depth Color depth or colour depth (see spelling differences), also known as bit depth, is either the number of bits used to indicate the color of a single pixel, or the number of bits used for each color component of a single pixel. When referring to ...
or palette size.


History

Computer researchers had long discussed the theoretical advantages of a framebuffer, but were unable to produce a machine with sufficient
memory Memory is the faculty of the mind by which data or information is encoded, stored, and retrieved when needed. It is the retention of information over time for the purpose of influencing future action. If past events could not be remembered, ...
at an economically practicable cost. In 1947, the
Manchester Baby The Manchester Baby, also called the Small-Scale Experimental Machine (SSEM), was the first electronic stored-program computer. It was built at the University of Manchester by Frederic Calland Williams, Frederic C. Williams, Tom Kilburn, and Ge ...
computer used a
Williams tube The Williams tube, or the Williams–Kilburn tube named after inventors Freddie Williams and Tom Kilburn, is an early form of computer memory. It was the first random-access digital storage device, and was used successfully in several early co ...
, later the Williams-Kilburn tube, to store 1024 bits on a cathode-ray tube (CRT) memory and displayed on a second CRT. Other research labs were exploring these techniques with
MIT Lincoln Laboratory The MIT Lincoln Laboratory, located in Lexington, Massachusetts, is a United States Department of Defense federally funded research and development center chartered to apply advanced technology to problems of national security. Research and dev ...
achieving a 4096 display in 1950. A color scanned display was implemented in the late 1960s, called the Brookhaven RAster Display (BRAD), which used a
drum memory Drum memory was a magnetic data storage device invented by Gustav Tauschek in 1932 in Austria. Drums were widely used in the 1950s and into the 1960s as computer memory. For many early computers, drum memory formed the main working memory ...
and a television monitor. In 1969, A. Michael Noll of
Bell Labs Nokia Bell Labs, originally named Bell Telephone Laboratories (1925–1984), then AT&T Bell Laboratories (1984–1996) and Bell Labs Innovations (1996–2007), is an American industrial research and scientific development company owned by mult ...
implemented a scanned display with a frame buffer, using
magnetic-core memory Magnetic-core memory was the predominant form of random access, random-access computer memory for 20 years between about 1955 and 1975. Such memory is often just called core memory, or, informally, core. Core memory uses toroids (rings) of a ...
. Later on, the Bell Labs system was expanded to display an image with a color depth of three bits on a standard color TV monitor. In the early 1970s, the development of
MOS memory Semiconductor memory is a digital electronic semiconductor device used for digital data storage, such as computer memory. It typically refers to devices in which data is stored within metal–oxide–semiconductor (MOS) memory cells on a sili ...
( metal-oxide-semiconductor memory) integrated-circuit chips, particularly high-density
DRAM Dynamic random-access memory (dynamic RAM or DRAM) is a type of random-access semiconductor memory that stores each bit of data in a memory cell, usually consisting of a tiny capacitor and a transistor, both typically based on metal-oxid ...
(dynamic
random-access memory Random-access memory (RAM; ) is a form of computer memory that can be read and changed in any order, typically used to store working Data (computing), data and machine code. A Random access, random-access memory device allows data items to b ...
) chips with at least 1 kb memory, made it practical to create, for the first time, a digital memory system with framebuffers capable of holding a standard video image. This led to the development of the
SuperPaint SuperPaint was a pioneering graphics program and framebuffer computer system developed by Richard Shoup at Xerox PARC. The system was first conceptualized in late 1972 and produced its first stable image in April 1973. SuperPaint was among the e ...
system by Richard Shoup at
Xerox PARC PARC (Palo Alto Research Center; formerly Xerox PARC) is a research and development company in Palo Alto, California. Founded in 1969 by Jacob E. "Jack" Goldman, chief scientist of Xerox Corporation, the company was originally a division of Xero ...
in 1972. Shoup was able to use the SuperPaint framebuffer to create an early digital video-capture system. By synchronizing the output signal to the input signal, Shoup was able to overwrite each pixel of data as it shifted in. Shoup also experimented with modifying the output signal using color tables. These color tables allowed the SuperPaint system to produce a wide variety of colors outside the range of the limited 8-bit data it contained. This scheme would later become commonplace in computer framebuffers. In 1974,
Evans & Sutherland Evans & Sutherland is a pioneering American computer firm in the computer graphics field. Its current products are used in digital projection environments like planetariums. Its simulation business, which it sold to Rockwell Collins, sold products ...
released the first commercial framebuffer, the Picture System, costing about $15,000. It was capable of producing resolutions of up to 512 by 512 pixels in 8-bit
grayscale In digital photography, computer-generated imagery, and colorimetry, a grayscale image is one in which the value of each pixel is a single sample representing only an ''amount'' of light; that is, it carries only intensity information. Graysca ...
, and became a boon for graphics researchers who did not have the resources to build their own framebuffer. The
New York Institute of Technology The New York Institute of Technology (NYIT or New York Tech) is a private research university founded in 1955. It has two main campuses in New York—one in Old Westbury, on Long Island, and one in Manhattan. Additionally, it has a cybersecu ...
would later create the first 24-bit color system using three of the Evans & Sutherland framebuffers. Each framebuffer was connected to an
RGB The RGB color model is an additive color model in which the red, green and blue primary colors of light are added together in various ways to reproduce a broad array of colors. The name of the model comes from the initials of the three addi ...
color output (one for red, one for green and one for blue), with a Digital Equipment Corporation PDP 11/04
minicomputer A minicomputer, or colloquially mini, is a class of smaller general purpose computers that developed in the mid-1960s and sold at a much lower price than mainframe and mid-size computers from IBM and its direct competitors. In a 1970 survey, ...
controlling the three devices as one. In 1975, the UK company
Quantel Quantel was a company based in the United Kingdom and founded in 1973 that designed and manufactured digital production equipment for the broadcast television, video production and motion picture industries. They were headquartered in Newbury, ...
produced the first commercial full-color broadcast framebuffer, the Quantel DFS 3000. It was first used in TV coverage of the 1976 Montreal Olympics to generate a
picture-in-picture Picture-in-picture (PiP) is a feature that can be found in television receivers, personal computers and smartphones, consisting of a video stream playing within an inset window, freeing the rest of the screen for other tasks. For televisions, pic ...
inset of the Olympic flaming torch while the rest of the picture featured the runner entering the stadium. The rapid improvement of integrated-circuit technology made it possible for many of the home computers of the late 1970s to contain low-color-depth framebuffers. Today, nearly all computers with graphical capabilities utilize a framebuffer for generating the video signal.
Amiga Amiga is a family of personal computers introduced by Commodore in 1985. The original model is one of a number of mid-1980s computers with 16- or 32-bit processors, 256 KB or more of RAM, mouse-based GUIs, and significantly improved graphi ...
computers, created in the 1980s, featured special design attention to graphics performance and included a unique
Hold-And-Modify Hold-And-Modify, usually abbreviated as HAM, is a display mode of the Commodore Amiga computer. It uses a highly unusual technique to express the color of pixels, allowing many more colors to appear on screen than would otherwise be possible ...
framebuffer capable of displaying 4096 colors. Framebuffers also became popular in high-end workstations and
arcade system board An arcade video game takes player input from its controls, processes it through electrical or computerized components, and displays output to an electronic monitor or similar display. Most arcade video games are coin-operated, housed in an arc ...
s throughout the 1980s.
SGI SGI may refer to: Companies *Saskatchewan Government Insurance *Scientific Games International, a gambling company *Silicon Graphics, Inc., a former manufacturer of high-performance computing products *Silicon Graphics International, formerly Rac ...
,
Sun Microsystems Sun Microsystems, Inc. (Sun for short) was an American technology company that sold computers, computer components, software, and information technology services and created the Java programming language, the Solaris operating system, ZFS, the ...
, HP, DEC and IBM all released framebuffers for their workstation computers in this period. These framebuffers were usually of a much higher quality than could be found in most home computers, and were regularly used in television, printing, computer modeling and 3D graphics. Framebuffers were also used by
Sega is a Japanese multinational corporation, multinational video game and entertainment company headquartered in Shinagawa, Tokyo. Its international branches, Sega of America and Sega Europe, are headquartered in Irvine, California and London, r ...
for its high-end arcade boards, which were also of a higher quality than on home computers.


Display modes

Framebuffers used in personal and home computing often had sets of defined ''modes'' under which the framebuffer can operate. These modes reconfigure the hardware to output different resolutions, color depths, memory layouts and
refresh rate The refresh rate (or "vertical refresh rate", "vertical scan rate", terminology originating with the cathode ray tubes) is the number of times per second that a raster-based display device displays a new image. This is independent from frame rate ...
timings. In the world of
Unix Unix (; trademarked as UNIX) is a family of multitasking, multiuser computer operating systems that derive from the original AT&T Unix, whose development started in 1969 at the Bell Labs research center by Ken Thompson, Dennis Ritchie, and ot ...
machines and operating systems, such conveniences were usually eschewed in favor of directly manipulating the hardware settings. This manipulation was far more flexible in that any resolution, color depth and refresh rate was attainable – limited only by the memory available to the framebuffer. An unfortunate side-effect of this method was that the
display device A display device is an output device for presentation of information in visual or tactile form (the latter used for example in tactile electronic displays for blind people). When the input information that is supplied has an electrical signal the ...
could be driven beyond its capabilities. In some cases, this resulted in hardware damage to the display. More commonly, it simply produced garbled and unusable output. Modern CRT monitors fix this problem through the introduction of protection circuitry. When the display mode is changed, the monitor attempts to obtain a signal lock on the new refresh frequency. If the monitor is unable to obtain a signal lock, or if the signal is outside the range of its design limitations, the monitor will ignore the framebuffer signal and possibly present the user with an error message. LCD monitors tend to contain similar protection circuitry, but for different reasons. Since the LCD must digitally sample the display signal (thereby emulating an electron beam), any signal that is out of range cannot be physically displayed on the monitor.


Color palette

Framebuffers have traditionally supported a wide variety of color modes. Due to the expense of memory, most early framebuffers used 1-bit (2-colors per pixel), 2-bit (4-colors), 4-bit (16-colors) or 8-bit (256-colors) color depths. The problem with such small color depths is that a full range of colors cannot be produced. The solution to this problem was
indexed color In computing, indexed color is a technique to manage digital images' colors in a limited fashion, in order to save computer memory and file storage, while speeding up display refresh and file transfers. It is a form of vector quantization comp ...
which adds a
lookup table In computer science, a lookup table (LUT) is an array that replaces runtime computation with a simpler array indexing operation. The process is termed as "direct addressing" and LUTs differ from hash tables in a way that, to retrieve a value v wi ...
to the framebuffer. Each color stored in framebuffer memory acts as a color index. The lookup table serves as a palette with a limited number of different colors meanwhile the rest is used as an index table. Here is a typical indexed 256-color image and its own palette (shown as a rectangle of swatches): : In some designs it was also possible to write data to the lookup table (or switch between existing palettes) on the run, allowing dividing the picture into horizontal bars with their own palette and thus render an image that had a far wider palette. For example, viewing an outdoor shot photograph, the picture could be divided into four bars, the top one with emphasis on sky tones, the next with foliage tones, the next with skin and clothing tones, and the bottom one with ground colors. This required each palette to have overlapping colors, but carefully done, allowed great flexibility.


Memory access

While framebuffers are commonly accessed via a memory mapping directly to the CPU memory space, this is not the only method by which they may be accessed. Framebuffers have varied widely in the methods used to access memory. Some of the most common are: * Mapping the entire framebuffer to a given memory range. * Port commands to set each pixel, range of pixels or palette entry. * Mapping a memory range smaller than the framebuffer memory, then
bank switching Bank switching is a technique used in computer design to increase the amount of usable memory beyond the amount directly addressable by the processor instructions. It can be used to configure a system differently at different times; for example ...
as necessary. The framebuffer organization may be
packed pixel In packed pixel or chunky framebuffer organization, the bits defining each pixel are clustered and stored consecutively. For example, if there are 16 bits per pixel, each pixel is represented in two consecutive (contiguous) 8-bit bytes in the frameb ...
or
planar Planar is an adjective meaning "relating to a plane (geometry)". Planar may also refer to: Science and technology * Planar (computer graphics), computer graphics pixel information from several bitplanes * Planar (transmission line technologies), ...
. The framebuffer may be
all points addressable A dot matrix is a 2-dimensional patterned array, used to represent characters, symbols and images. Most types of modern technology use dot matrices for display of information, including mobile phones, televisions, and printers. The system is al ...
or have restrictions on how it can be updated.


RAM on the video card

Video cards always have a certain amount of RAM. A small portion of this RAM is where the bitmap of image data is "buffered" for display. The term ''frame buffer'' is thus often used interchangeably when referring to this RAM. The CPU sends image updates to the video card. The video processor on the card forms a picture of the screen image and stores it in the frame buffer as a large bitmap in RAM. The bitmap in RAM is used by the card to continually refresh the screen image.


Virtual framebuffers

Many systems attempt to emulate the function of a framebuffer device, often for reasons of compatibility. The two most common virtual framebuffers are the
Linux framebuffer The Linux framebuffer (fbdev) is a linux subsystem used to show graphics on a computer monitor, typically on the system console. It was designed as a hardware-independent API to give user space software access to the framebuffer (the part of ...
device (fbdev) and the X Virtual Framebuffer (
Xvfb Xvfb or X virtual framebuffer is a display server implementing the X11 display server protocol. In contrast to other display servers, Xvfb performs all graphical operations in virtual memory without showing any screen output. From the point of v ...
). Xvfb was added to the
X Window System The X Window System (X11, or simply X) is a windowing system for bitmap displays, common on Unix-like operating systems. X provides the basic framework for a GUI environment: drawing and moving windows on the display device and interacting wit ...
distribution to provide a method for running X without a graphical framebuffer. The Linux framebuffer device was developed to abstract the physical method for accessing the underlying framebuffer into a guaranteed memory map that is easy for programs to access. This increases portability, as programs are not required to deal with systems that have disjointed memory maps or require
bank switching Bank switching is a technique used in computer design to increase the amount of usable memory beyond the amount directly addressable by the processor instructions. It can be used to configure a system differently at different times; for example ...
.


Page flipping

A frame buffer may be designed with enough memory to store two frames worth of video data. In a technique known generally as
double buffering In computer science, multiple buffering is the use of more than one buffer to hold a block of data, so that a "reader" will see a complete (though perhaps old) version of the data, rather than a partially updated version of the data being creat ...
or more specifically as page flipping, the framebuffer uses half of its memory to display the current frame. While that memory is being displayed, the other half of memory is filled with data for the next frame. Once the secondary buffer is filled, the framebuffer is instructed to display the secondary buffer instead. The primary buffer becomes the secondary buffer, and the secondary buffer becomes the primary. This switch is often done after the
vertical blanking interval In a raster scan display, the vertical blanking interval (VBI), also known as the vertical interval or VBLANK, is the time between the end of the final visible line of a frame or field and the beginning of the first visible line of the next fram ...
to avoid
screen tearing Screen tearing is a visual artifact in video display where a display device shows information from multiple frames in a single screen draw. The artifact occurs when the video feed to the device is not synchronized with the display's refresh rat ...
where half the old frame and half the new frame is shown together. Page flipping has become a standard technique used by PC
game programmer A game programmer is a software engineer, programmer, or computer scientist who primarily develops codebases for video game Video games, also known as computer games, are electronic games that involves interaction with a user interface ...
s.


Graphics accelerators

As the demand for better graphics increased, hardware manufacturers created a way to decrease the amount of CPU time required to fill the framebuffer. This is commonly called ''graphics acceleration''. Common graphics drawing commands (many of them geometric) are sent to the graphics accelerator in their raw form. The accelerator then rasterizes the results of the command to the framebuffer. This method frees the CPU to do other work. Early accelerators focused on improving the performance of 2D
GUI The GUI ( "UI" by itself is still usually pronounced . or ), graphical user interface, is a form of user interface that allows users to interact with electronic devices through graphical icons and audio indicator such as primary notation, inste ...
systems. While retaining these 2D capabilities, most modern accelerators focus on producing 3D imagery in real time. A common design uses a
graphics library A graphics library is a program library designed to aid in rendering computer graphics to a monitor. This typically involves providing optimized versions of functions that handle common rendering tasks. This can be done purely in software and runn ...
such as
OpenGL OpenGL (Open Graphics Library) is a cross-language, cross-platform application programming interface (API) for rendering 2D and 3D vector graphics. The API is typically used to interact with a graphics processing unit (GPU), to achieve hardwa ...
or
Direct3D Direct3D is a graphics application programming interface (API) for Microsoft Windows. Part of DirectX, Direct3D is used to render three-dimensional graphics in applications where performance is important, such as games. Direct3D uses hardware a ...
which interfaces with the graphics driver to translate received commands to instructions for the accelerator's
graphics processing unit A graphics processing unit (GPU) is a specialized electronic circuit designed to manipulate and alter memory to accelerate the creation of images in a frame buffer intended for output to a display device. GPUs are used in embedded systems, mobi ...
(GPU). The GPU uses those instructions to compute the rasterized results and the results are
bit blit Bit blit (also written BITBLT, BIT BLT, BitBLT, Bit BLT, Bit Blt etc., which stands for ''bit block transfer'') is a data operation commonly used in computer graphics in which several bitmaps are combined into one using a ''boolean function''. The ...
ted to the framebuffer. The framebuffer's signal is then produced in combination with built-in video overlay devices (usually used to produce the mouse cursor without modifying the framebuffer's data) and any final special effects that are produced by modifying the output signal. An example of such final special effects was the
spatial anti-aliasing In digital signal processing, spatial anti-aliasing is a technique for minimizing the distortion artifacts (aliasing) when representing a high-resolution image at a lower resolution. Anti-aliasing is used in digital photography, computer graphics ...
technique used by the 3dfx Voodoo cards. These cards add a slight blur to output signal that makes aliasing of the rasterized graphics much less obvious. At one time there were many manufacturers of graphics accelerators, including:
3dfx Interactive 3dfx Interactive was an American technology company headquartered in San Jose, California, founded in 1994, that specialized in the manufacturing of 3D graphics processing units, and later, video cards. It was a pioneer in the field from the l ...
;
ATI Ati or ATI may refer to: * Ati people, a Negrito ethnic group in the Philippines **Ati language (Philippines), the language spoken by this people group ** Ati-Atihan festival, an annual celebration held in the Philippines *Ati language (China), a ...
;
Hercules Hercules (, ) is the Roman equivalent of the Greek divine hero Heracles, son of Jupiter and the mortal Alcmena. In classical mythology, Hercules is famous for his strength and for his numerous far-ranging adventures. The Romans adapted the Gr ...
;
Trident A trident is a three- pronged spear. It is used for spear fishing and historically as a polearm. The trident is the weapon of Poseidon, or Neptune, the God of the Sea in classical mythology. The trident may occasionally be held by other marine ...
;
Nvidia Nvidia CorporationOfficially written as NVIDIA and stylized in its logo as VIDIA with the lowercase "n" the same height as the uppercase "VIDIA"; formerly stylized as VIDIA with a large italicized lowercase "n" on products from the mid 1990s to ...
;
Radius In classical geometry, a radius ( : radii) of a circle or sphere is any of the line segments from its center to its perimeter, and in more modern usage, it is also their length. The name comes from the latin ''radius'', meaning ray but also the ...
;
S3 Graphics S3 Graphics, Ltd (commonly referred to as S3) was an American computer graphics company. The company sold the Trio, ViRGE, Savage 3D, and Chrome series of graphics processors. Struggling against competition from 3dfx Interactive, ATI and Nvid ...
; SiS and
Silicon Graphics Silicon Graphics, Inc. (stylized as SiliconGraphics before 1999, later rebranded SGI, historically known as Silicon Graphics Computer Systems or SGCS) was an American high-performance computing manufacturer, producing computer hardware and soft ...
. the market for graphics accelerators for x86-based systems is dominated by Nvidia (acquired 3dfx in 2002),
AMD Advanced Micro Devices, Inc. (AMD) is an American multinational semiconductor company based in Santa Clara, California, that develops computer processors and related technologies for business and consumer markets. While it initially manufactur ...
(who acquired ATI in 2006), and
Intel Intel Corporation is an American multinational corporation and technology company headquartered in Santa Clara, California. It is the world's largest semiconductor chip manufacturer by revenue, and is one of the developers of the x86 seri ...
.


Comparisons

With a framebuffer, the electron beam (if the display technology uses one) is commanded to perform a
raster scan A raster scan, or raster scanning, is the rectangular pattern of image capture and reconstruction in television. By analogy, the term is used for raster graphics, the pattern of image storage and transmission used in most computer bitmap image s ...
, the way a
television Television, sometimes shortened to TV, is a telecommunication medium for transmitting moving images and sound. The term can refer to a television set, or the medium of television transmission. Television is a mass medium for advertisin ...
renders a broadcast signal. The color information for each point thus displayed on the screen is pulled directly from the framebuffer during the scan, creating a set of discrete picture elements, i.e. pixels. Framebuffers differ significantly from the
vector display A vector monitor, vector display, or calligraphic display is a display device used for computer graphics up through the 1970s. It is a type of CRT, similar to that of an early oscilloscope. In a vector display, the image is composed of drawn li ...
s that were common prior to the advent of raster graphics (and, consequently, to the concept of a framebuffer). With a vector display, only the vertices of the graphics primitives are stored. The
electron beam Cathode rays or electron beam (e-beam) are streams of electrons observed in discharge tubes. If an evacuated glass tube is equipped with two electrodes and a voltage is applied, glass behind the positive electrode is observed to glow, due to ele ...
of the output display is then commanded to move from vertex to vertex, tracing a line across the area between these points. Likewise, framebuffers differ from the technology used in early
text mode Text mode is a computer display mode in which content is internally represented on a computer screen in terms of characters rather than individual pixels. Typically, the screen consists of a uniform rectangular grid of ''character cells'', each ...
displays, where a buffer holds codes for characters, not individual pixels. The video display device performs the same raster scan as with a framebuffer, but generates the pixels of each character in the buffer as it directs the beam.


See also

*
Bit plane A bit plane of a digital discrete signal (such as image or sound) is a set of bits corresponding to a given bit position in each of the binary numbers representing the signal. For example, for 16-bit data representation there are 16 bit plane ...
*
Scanline rendering Scanline rendering (also scan line rendering and scan-line rendering) is an algorithm for visible surface determination, in 3D computer graphics, that works on a row-by-row basis rather than a polygon-by-polygon or pixel-by-pixel basis. All of t ...
* Swap chain *
Tile-based video game A tile-based video game is a type of video or video game where the playing area consists of small square (or, much less often, rectangular, parallelogram, or hexagonal) graphic images referred to as ''tiles'' laid out in a grid. That the screen ...
*
Tiled rendering Tiled rendering is the process of subdividing a computer graphics image by a regular grid in optical space and rendering each section of the grid, or ''tile'', separately. The advantage to this design is that the amount of memory and bandwidth is re ...


References

* * *


External links


Interview with NYIT researcher discussing the 24-bit system


{{Graphics Processing Unit Computer graphics Computer memory Image processing User interfaces