computer graphics

1. The set of technologies used to create art with computers.
2. Art or designs created using such technologies.

A branch of computer science that deals with the theory and techniques of computer image synthesis. Computers produce images by analyzing a collection of dots, or pixels (picture elements). Computer graphics is used to enhance the transfer and understanding of information in science, engineering, medicine, education, and business by facilitating the generation, production, and display of synthetic images of natural objects with realism almost indistinguishable from photographs. Computer graphics facilitates the production of images that range in complexity from simple line drawings to three-dimensional reconstructions of data obtained from computerized axial tomography (CAT) scans in medical applications. User interaction can be increased through animation, which conveys large amounts of information by seemingly bringing to life multiple related images. Animation is widely used in entertainment, education, industry, flight simulators, scientific research, and heads-up displays (devices which allow users to interact with a virtual world). Virtual-reality applications permit users to interact with a three-dimensional world, for example, by “grabbing” objects and manipulating objects in the world. Digital image processing is a companion field to computer graphics. However, image processing, unlike computer graphics, generally begins with some image in image space, and performs operations on the components (pixels) to produce new images. See also Image processing.

Computers are equipped with special hardware to display images. Several types of image presentation or output devices convert digitally represented images into visually perceptible pictures. They include pen-and-ink plotters, dot-matrix plotters, electrostatic or laser-printer plotters, storage tubes, liquid-crystal displays (LCDs), active matrix panels, plasma panels, and cathode-ray-tube (CRT) displays. Images can be displayed by a computer on a cathode-ray tube in two different ways: raster scan and random (vector) scan. See also Cathode-ray tube; Computer peripheral devices.

Interaction with the object takes place via devices attached to the computer, starting with the keyboard and the mouse. Each type of device can be programmed to deliver various types of functionality. The quality and ease of use of the user interface often determines whether users enjoy a system and whether the system is successful. Interactive graphics aids the user in the creation and modification of graphical objects and the response to these objects in real-time. The most commonly used input device is the mouse. Other kinds of interaction devices include the joystick, trackball, light pen, and data tablet. Some of these two-dimensional (2D) devices can be modified to extend to three dimensions (3D). The data glove is a device capable of recording hand movements. The data glove is capable of a simple gesture recognition and general tracking of hand orientation.

In the production of a computer-generated image, the designer has to specify the objects in the image and their shapes, positions, orientations, and surface colors or textures. Further, the viewer's position and direction of view (camera orientation) must be specified. The software should calculate the parts of all objects that can be seen by the viewer (camera). Only the visible portions of the objects should be displayed (captured on the film). (This requirement is referred to as the hidden-surface problem.) The rendering software is then applied to compute the amount and color of light reaching the viewer eye (film) at any point in the image, and then to display that point. Some modern graphics work stations have special hardware to implement projections, hidden-surface elimination, and direct illumination. Everything else in image generation is done in software.

Solid modeling is a technique used to represent three-dimensional shapes in a computer. The importance of solid modeling in computer-aided design and manufacturing (CAD/CAM) systems has been increasing. Engineering applications ranging from drafting to the numerical control of machine tools increasingly rely on solid modeling techniques. Solid modeling uses three-dimensional solid primitives (the cube, sphere, cone, cylinder, and ellipsoid) to represent three-dimensional objects. Complex objects can be constructed by combining the primitives. See also Computer-aided design and manufacturing; Computer-aided engineering.

The creation of images by simulating a model of light propagation is often called image synthesis. The goal of image synthesis is often stated as photorealism, that is, the criterion that the image look as good as a photograph. Rendering is a term used for methods or techniques that are used to display realistic-looking three-dimensional images on a two-dimensional medium such as the cathode-ray-tube screen (see illustration). The display of a wire-frame image is one way of rendering the object. The most common method of rendering is shading. Generally, rendering includes addition of texture, shadows, and the color of light that reaches the observer's eye from any point in the image.

Image renderings of a teapot. (a) Wire-frame model with 512 polygons. (b) Smooth shading (non-shiny). (A. Tokuta, Technical Report, Department of Computer Science and Engineering, University of South Florida)

Computer-generated images are used extensively in the entertainment world and other areas. Realistic images have become essential tools in research and education. Conveying realism in these images may depend on the convincing generation of natural phenomena. A fundamental difficulty is the complexity of the real world. Existing models are based on physical or biological concepts. The behavior of objects can be determined by physical properties or chemical and microphysical properties.

Pictures created and manipulated through the use of computer devices. The term computer graphics generally pertains to any computer device or program that makes a computer capable of displaying and manipulating pictures. For example: a laser printer is said to be a computer graphics device because it allows the computer to output pictures; likewise, a computer display monitor can display pictures. Computer graphics are used for various applications including publishing, education, entertainment, and advertising, or wherever pictures are deemed reasonable or necessary in the creation of a message. They are also used very effectively in situations where there is a need for computed data to be visualized, such as in statistical charts or graphs of mathematical data. Most computer graphics can also be drawn by an artist, but the computer can accomplish much more in a much shorter period of time. One of the major benefits of computer graphics is that images can be manipulated with relative ease and that a multitude of visual effects are possible because the images can be played with over and over again until a desired effect is achieved.

The basic building block of images on a computer screen is a dot of light called a pixel—the word created by combining the words "picture" and "element."

The computer, because it can present thousands of pixels on a computer screen in millions of different colors, can create shapes that the human eye recognizes as an image—a computer graphic.

It is hard now to imagine a world without computer graphics. Today's children have grown up with video games, and graphic designers work almost exclusively with computer programs to create images once laboriously drawn with pen, compass, ruler, and T-square on paper. Pilots learn the latest techniques of flying in flight simulators; engineers and architects design everything from aircraft to skyscrapers, making three-dimensional models with their computers; TV weather maps display precipitation as it occurs; and doctors can look inside a patient's body without breaking the skin.

It was in the early 1960s that computer pioneers at leading universities began developing computers and the graphics programs that have revolutionized the way we create visual images. The invention of the video display terminal, or computer monitor or screen, and its widespread use beginning in the 1970s, led to the revolution in the way computers were put to use. This revolution was accelerated by the introduction of the photocopier and the electronic spreadsheet to the computer field.

The photocopier was invented by Chester Carlson in 1940 and first produced commercially by Xerox Corporation in 1959. The photo-copier's cousin, the desktop laser printer, along with software for desktop publishing (a term coined in the early 1980s), made it possible for amateurs to create polished newsletters, flyers, party invitations, and other documents for modest-sized audiences. Now, with the use of scanners, individuals can produce documents containing color photos, original drawings, or any graphic image from a publication or the Internet with permission from the owners of those images.

Electronic spreadsheets, which appeared in 1978, incorporated mathematical formulas behind each element in a table of data. These formulas could refer to other elements of the table. Any change in one value would immediately affect the other cells, so business projections such as sales, growth, or changes in interest rates could be manipulated to explore "what if" scenarios; the impact of every change would be instantly apparent. Such tables can then be imported via computers into a text document to clarify and enhance the information in the document.

Computer memory and speed seem to expand by the day, along with the sophistication of graphics programs, allowing individuals in their own homes and offices to produce graphic materials that match or exceed the capabilities of even the most advanced printing firms only a few years ago.

To create a graphic image, a computer program will supply a series of instructions. Those instructions will tell a computer how to connect two points to form a straight line, draw a circle, or form a letter in printed text. To accomplish this, computer scientists have devised methods to break down complex drawing tasks to simple components. The computer program then repeats those drawing tasks over and over to form a complete image.

Drawing an image of a brick wall by hand, for example, would require an artist or draftsperson to draw hundreds or thousands of rectangles individually. The computer, on the other hand, would draw one brick, then using the same mathematical formula it used to create the first brick, would duplicate it thousands of times almost instantaneously.

Computers are excellent number crunchers. The thousands of calculations—even simple addition or subtraction calculations—needed to create a computer image would be an immensely time-consuming process without computers. But with these calculations written into a computer graphics program, the computer will quickly and precisely light up the pixels needed to create the desired graphic image on the video monitor.

Pixels are arranged in rows and columns on a screen. The number of pixels in rows times the number of pixels in columns determines their density, or resolution. Resolution is one component of the computer's ability to form a distinguishable image. A typical computer screen contains 640 pixels in a line and 480 pixels vertically. Multiplied, the number of pixels on a typical screen equals 307,200.

To draw the simplest graphics—those in black and white—the computer program will assign the number 1 to those pixels that are to be lighted and 0 to those that will remain unlit. The contrast created between lighted and unlighted dots forms the graphic image. Numbers written into computer programs likewise determine the color of each pixel in a color system.

Although the ability of computer hardware and software to produce a dense or high-resolution image is important to creating a quality image, their ability to duplicate colors is even more important.

Primary colors—reds, greens, and blues— can be combined to produce full or true color. Their lightness or darkness—or values—as well as their color create shapes, just as they would in a painting or drawing.

The number of pieces of information (bits) set aside for each pixel in a region of computer memory known as the video buffer determines how many colors the screen can display at once. A true color system is capable of displaying more than 16.7 million colors. However, because of the limits of computer memory, ordinary computers employ a 256-color system.

A program will command the use of one of the 256 colors from a color palette, which in turn will transfer that color to a pixel. Determining the numbers to achieve the desired color and value is the core of the science of computer graphics.

By limiting the possible colors to 256, each pixel cannot be illuminated with the perfect color. However, the computer, through a process called dithering, can fool the eye by blending colors among adjacent pixels. If a particular red color is not available from the color palette, the computer will spread its available red values around adjacent pixels—giving more red values and fewer green and blue values to some while giving fewer red values and more green and blue values to others to achieve the desired overall color. The process of dithering starts at the image's upper-left corner. In turn the computer will dither each pixel's red, blue, and green color values to make the image appear to the eye as color-accurate, ending at the lower-right corner of the image.

In addition to dithering, a computer can reproduce a true color image, such as a photograph containing thousands of colors, with accuracy by optimizing the use of the 256 colors available through the computer's palette.

One such technique counts the number of colors in an image and gives priority to the ones used the most. But this leaves some colors unrepresented and thus unavailable where needed. To solve this problem, a computer program will carve up an image containing several thousand colors into 256 equal "blocks" grouped according to their intensity of color. It discards the blocks with no or few dots. The remaining pixels are then divided up into 256 blocks with an equal number of pixels.

With color space divided up this way, the average of all the pixel values in each block represents an optimal choice for a palette color.

When a computer graphics program draws a line or circle, it chooses which of the pixels to illuminate on a line from point A to point B, for example, by a simple method of addition and subtraction. First the computer illuminates the pixel at point A. Then the computer moves toward B one pixel closer. Should it illuminate the pixel on the same rowor one on the row above or below? A simple calculation shows the computer which of the two pixels lies closer to the ideal line, and it illuminates that pixel.

In milliseconds, the program continues to move along the line, calculating which pixel to illuminate until it reaches point B, creating a line that is not strictly straight, but straight enough to appear so to the eye.

Just as with lines, the program will create any shape—triangle, square, or polygon—using a mathematical formula pertaining to that shape. Circles are created in much the same way. The program will choose which pixel to illuminate by measuring its distance from the center of the circle and calculating whether the one at that point along the circumference will help create the circle's ideal shape. Again, the circle is not perfectly circular, but the eye is somewhat deceived because each pixel that is illuminated differs only slightly from its neighbor.

Because computer graphic images can require large amounts of computer memory to be reproducible, techniques have been developed to reduce, or compress, the number of bits of memory needed to store the image.

One such image compression technique is named run-length encoding (RLE) .Ituses markers that stand for runs of repeating numbers in a graphics file, reducing to two—one specifying the number and another the number of that number in a run—in a file. For example, a file that contains 50 identically colored red pixels with a value of 200 can be substituted with the numbers 50 and 200. With this process, the computer knows the image requires 50 characters with a 200 red value, but it stores only those two commands, a one-twenty-fifth reduction.

Another compression method, JPEG, takes its name from, the Joint Photographic Experts Group, the organization that invented it. It uses mathematical formulas to segregate information about an image by its importance, and then discards the less important information. The image that results after such compression will not exactly match the original, since some information has been lost in the process.

Another important file format is the Tagged-Image File Format (TIFF) which can be read in either IBM-PC-compatible or Macintosh computers.

To create three-dimensional images, a computer uses a mathematical transformation called a projection. Although the images are presented on a two-dimensional screen, the computer, through using the principle of perspective— foreshortening, shading, and hidden surface removal—and through its ability to make quick calculations, can portray the object so as to make it appear to the human eye as a three-dimensional object. These techniques are the basis for computer-aided drafting and computer animation.

Rapidly changing 3-D images on the computer screen creates the illusion of motion, or animation. An animated movie will use slightly differing images on a filmstrip to create the illusion of motion. A computer acts much the same way, although it cannot produce the twenty-four full-screen images per second typical in an animated film.

The computer, however, will accomplish the same effect by displaying one image on the screen while creating a new image in the background and swapping the screen. This eliminates the time between display of the images, creating the illusion of motion.

Bibliography

Gates, Bill. (1995). The Road Ahead. New York: Viking Penguin.

Prosise, Jeff. (1994). How Computer Graphics Work. Emeryville, CA: Ziff-Davis Press.

[Article by: WALTER A. HAMILTON]

The use of computers to create illustrations or designs.

Images constructed under computer control, displayed on a cathode ray tube.

For more information on computer graphics, visit Britannica.com.

This article is about graphics created using computers. For the article about the scientific study of computer graphics, see Computer graphics (computer science). For other uses, see Computer graphics (disambiguation).

A Blender 2.45 screenshot.

A 2D projection of a 3D projection of a 4D Pentachoron performing a double rotation about two orthogonal planes.

Computer graphics are graphics created using computers and, more generally, the representation and manipulation of pictorial data by a computer.

The development of computer graphics has made computers easier to interact with and better for understanding and interpreting many types of data. Developments in computer graphics have had a profound impact on many types of media and have revolutionized the animation and video game industry.

Contents 1 Overview 2 History 3 Image types 3.1 2D computer graphics 3.1.1 Pixel art 3.1.2 Vector graphics 3.2 3D computer graphics 3.3 Computer animation 4 Concepts and Principles 4.1 Image 4.2 Pixel 4.3 Graphics 4.4 Rendering 4.5 Volume rendering 4.6 3D modeling 5 Pioneers in graphic design 6 The study of computer graphics 6.1 Connected studies 7 Applications 8 References 9 Further reading 10 External links

Overview

The term computer graphics includes almost everything on computers that is not text or sound. Today nearly all computers use some graphics and users expect to control their computer through icons and pictures rather than just by typing.^[1] The term Computer Graphics has several meanings:

• the representation and manipulation of pictorial data by a computer
• the various technologies used to create and manipulate such pictorial data
• the images so produced, and
• the sub-field of computer science which studies methods for digitally synthesizing and manipulating visual content, see study of computer graphics

Today computers and computer-generated images touch many aspects of our daily life. Computer imagery is found on television, in newspapers, in weather reports, and during surgical procedures. A well-constructed graph can present complex statistics in a form that is easier to understand and interpret. Such graphs are used to illustrate papers, reports, theses, and other presentation material. A range of tools and facilities are available to enable users to visualize their data, and computer graphics are used in many disciplines. ^[2]

History

The phrase “Computer Graphics” was coined in 1960 by William Fetter, a graphic designer for Boeing.^[3] The field of computer graphics developed with the emergence of computer graphics hardware. Early projects like the Whirlwind and SAGE Projects introduced the CRT as a viable display and interaction interface and introduced the light pen as an input device.

SAGE Sector Control Room.

Further advances in computing led to greater advancements in interactive computer graphics. In 1959, the TX-2 computer was developed at MIT's Lincoln Laboratory. The TX-2 integrated a number of new man-machine interfaces. A light pen could be used to draw sketches on the computer using Ivan Sutherland's revolutionary Sketchpad software. The development of Sketchpad made Ivan Sutherland the "grandfather" of interactive computer graphics and graphical user interfaces.^[3]

The research at MIT would help shape the early computer and computer graphics industries. Major corporations soon became interested in the technology. IBM quickly responded by releasing the IBM 2250 graphics terminal, the first commercially available graphics computer.^[4] Several computer graphics companies were founded in the mid 1960s including TRW, Lockheed-Georgia, General Electric and Sperry Rand.

In 1969, the ACM initiated A Special Interest Group in Graphics (SIGGRAPH) which organizes conferences, graphics standards, and publications within the field of computer graphics. In 1973, the first annual SIGGRAPH conference was held, which has become one of the focuses of the organization. SIGGRAPH has grown in size and importance as the field of computer graphics has expanded over time. Many of the most important early breakthroughs in computer graphics research occurred at the University of Utah in the 1970s.

In the 1980s, artists and graphic designers began to see the personal computer, particularly the Commodore Amiga and Macintosh, as a serious design tool, one that could save time and draw more accurately than other methods. In the late 1980s, SGI computers were used to create some of the first fully computer-generated short films at Pixar. The Macintosh remains a highly popular tool for computer graphics among graphic design studios and businesses. Modern computers, dating from the 1980s often use graphical user interfaces (GUI) to present data and information with symbols, icons and pictures, rather than text. Graphics are one of the five key elements of multimedia technology.

3D graphics became more popular in the 1990s in gaming, multimedia and animation. In 1996, Quake, one of the first fully 3D games, was released. In 1995, Toy Story, the first full-length computer-generated animation film, was released in cinemas worldwide. Since then, computer graphics have only become more detailed and realistic, due to more powerful graphics hardware and 3D modeling software.

Image types

2D computer graphics

Raster graphic sprites (left) and masks (right)

2D computer graphics are the computer-based generation of digital images—mostly from two-dimensional models, such as 2D geometric models, text, and digital images, and by techniques specific to them. The word may stand for the branch of computer science that comprises such techniques, or for the models themselves.

2D computer graphics are mainly used in applications that were originally developed upon traditional printing and drawing technologies, such as typography, cartography, technical drawing, advertising, etc.. In those applications, the two-dimensional image is not just a representation of a real-world object, but an independent artifact with added semantic value; two-dimensional models are therefore preferred, because they give more direct control of the image than 3D computer graphics, whose approach is more akin to photography than to typography.

Pixel art

Pixel art is a form of digital art, created through the use of raster graphics software, where images are edited on the pixel level. Graphics in most old (or relatively limited) computer and video games, graphing calculator games, and many mobile phone games are mostly pixel art.

Vector graphics

Example showing effect of vector graphics versus raster graphics.

Vector graphics formats are complementary to raster graphics, which is the representation of images as an array of pixels, as it is typically used for the representation of photographic images.^[5] There are instances when working with vector tools and formats is best practice, and instances when working with raster tools and formats is best practice. There are times when both formats come together. An understanding of the advantages and limitations of each technology and the relationship between them is most likely to result in efficient and effective use of tools.

3D computer graphics

3D computer graphics in contrast to 2D computer graphics are graphics that use a three-dimensional representation of geometric data that is stored in the computer for the purposes of performing calculations and rendering 2D images. Such images may be for later display or for real-time viewing.

Despite these differences, 3D computer graphics rely on many of the same algorithms as 2D computer vector graphics in the wire frame model and 2D computer raster graphics in the final rendered display. In computer graphics software, the distinction between 2D and 3D is occasionally blurred; 2D applications may use 3D techniques to achieve effects such as lighting, and primarily 3D may use 2D rendering techniques.

3D computer graphics are often referred to as 3D models. Apart from the rendered graphic, the model is contained within the graphical data file. However, there are differences. A 3D model is the mathematical representation of any three-dimensional object (either inanimate or living). A model is not technically a graphic until it is visually displayed. Due to 3D printing, 3D models are not confined to virtual space. A model can be displayed visually as a two-dimensional image through a process called 3D rendering, or used in non-graphical computer simulations and calculations.

Computer animation

An example of Computer animation produced using Motion capture

Computer animation is the art of creating moving images via the use of computers. It is a subfield of computer graphics and animation. Increasingly it is created by means of 3D computer graphics, though 2D computer graphics are still widely used for stylistic, low bandwidth, and faster real-time rendering needs. Sometimes the target of the animation is the computer itself, but sometimes the target is another medium, such as film. It is also referred to as CGI (Computer-generated imagery or computer-generated imaging), especially when used in films.

Virtual entities may contain and be controlled by assorted attributes, such as transform values (location, orientation, scale; see Cartesian coordinate system) stored in an object's transformation matrix. Animation is the change of an attribute over time. Multiple methods of achieving animation exist; the rudimentary form is based on the creation and editing of keyframes, each storing a value at a given time, per attribute to be animated. The 2D/3D graphics software will interpolate between keyframes, creating an editable curve of a value mapped over time, resulting in animation. Other methods of animation include procedural and expression-based techniques: the former consolidates related elements of animated entities into sets of attributes, useful for creating particle effects and crowd simulations; the latter allows an evaluated result returned from a user-defined logical expression, coupled with mathematics, to automate animation in a predictable way (convenient for controlling bone behavior beyond what a hierarchy offers in skeletal system set up).

To create the illusion of movement, an image is displayed on the computer screen then quickly replaced by a new image that is similar to the previous image, but shifted slightly. This technique is identical to the illusion of movement in television and motion pictures.

Concepts and Principles

Image

In common usage, an image or picture is an artifact, usually two-dimensional, that has a similar appearance to some subject—usually a physical object or a person. Images may be two-dimensional, such as a photograph, screen display, and as well as a three-dimensional, such as a statue. They may be captured by optical devices—such as cameras, mirrors, lenses, telescopes, microscopes, etc. and natural objects and phenomena, such as the human eye or water surfaces.

A digital image is a representation of a two-dimensional image using ones and zeros (binary). Depending on whether or not the image resolution is fixed, it may be of vector or raster type. Without qualifications, the term "digital image" usually refers to raster images.

Pixel

In the enlarged portion of the image individual pixels are rendered as squares and can be easily seen.

In digital imaging, a pixel is the smallest piece of information in an image.^[6] Pixels are normally arranged in a regular 2-dimensional grid, and are often represented using dots or squares. Each pixel is a sample of an original image, where more samples typically provide a more accurate representation of the original. The intensity of each pixel is variable; in color systems, each pixel has typically three or four components such as red, green, and blue, or cyan, magenta, yellow, and black.

Graphics

Graphics are visual presentations on some surface, such as a wall, canvas, computer screen, paper, or stone to brand, inform, illustrate, or entertain. Examples are photographs, drawings, line art, graphs, diagrams, typography, numbers, symbols, geometric designs, maps, engineering drawings, or other images. Graphics often combine text, illustration, and color. Graphic design may consist of the deliberate selection, creation, or arrangement of typography alone, as in a brochure, flier, poster, web site, or book without any other element. Clarity or effective communication may be the objective, association with other cultural elements may be sought, or merely, the creation of a distinctive style.

Rendering

Rendering is the process of generating an image from a model, by means of computer programs. The model is a description of three dimensional objects in a strictly defined language or data structure. It would contain geometry, viewpoint, texture, lighting, and shading information. The image is a digital image or raster graphics image. The term may be by analogy with an "artist's rendering" of a scene. 'Rendering' is also used to describe the process of calculating effects in a video editing file to produce final video output.

3D projection

3D projection is a method of mapping three dimensional points to a two dimensional plane. As most current methods for displaying graphical data are based on planar two dimensional media, the use of this type of projection is widespread, especially in computer graphics, engineering and drafting.

Ray tracing

Ray tracing is a technique for generating an image by tracing the path of light through pixels in an image plane. The technique is capable of producing a very high degree of photorealism; usually higher than that of typical scanline rendering methods, but at a greater computational cost.

Shading

Example of shading.

Shading refers to depicting depth in 3D models or illustrations by varying levels of darkness. It is a process used in drawing for depicting levels of darkness on paper by applying media more densely or with a darker shade for darker areas, and less densely or with a lighter shade for lighter areas. There are various techniques of shading including cross hatching where perpendicular lines of varying closeness are drawn in a grid pattern to shade an area. The closer the lines are together, the darker the area appears. Likewise, the farther apart the lines are, the lighter the area appears. The term has been recently generalized to mean that shaders are applied. Dr. Anigbogu

Texture mapping

Texture mapping is a method for adding detail, surface texture, or colour to a computer-generated graphic or 3D model. Its application to 3D graphics was pioneered by Dr Edwin Catmull in 1974. A texture map is applied (mapped) to the surface of a shape, or polygon. This process is akin to applying patterned paper to a plain white box. Multitexturing is the use of more than one texture at a time on a polygon.^[7] Procedural textures (created from adjusting parameters of an underlying algorithm that produces an output texture), and bitmap textures (created in an image editing application) are, generally speaking, common methods of implementing texture definition from a 3D animation program, while intended placement of textures onto a model's surface often requires a technique known as UV mapping.

Volume rendering

Volume rendered CT scan of a forearm with different colour schemes for muscle, fat, bone, and blood.

Volume rendering is a technique used to display a 2D projection of a 3D discretely sampled data set. A typical 3D data set is a group of 2D slice images acquired by a CT or MRI scanner.

Usually these are acquired in a regular pattern (e.g., one slice every millimeter) and usually have a regular number of image pixels in a regular pattern. This is an example of a regular volumetric grid, with each volume element, or voxel represented by a single value that is obtained by sampling the immediate area surrounding the voxel.

3D modeling

3D modeling is the process of developing a mathematical, wireframe representation of any three-dimensional object, called a "3D model", via specialized software. Models may be created automatically or manually; the manual modeling process of preparing geometric data for 3D computer graphics is similar to plastic arts such as sculpting. 3D models may be created using multiple approaches: use of NURBS curves to generate accurate and smooth surface patches, polygonal mesh modeling (manipulation of faceted geometry), or polygonal mesh subdivision (advanced tessellation of polygons, resulting in smooth surfaces similar to NURBS models). A 3D model can be displayed as a two-dimensional image through a process called 3D rendering, used in a computer simulation of physical phenomena, or animated directly for other purposes. The model can also be physically created using 3D Printing devices.

Pioneers in graphic design

Charles Csuri

Charles Csuri is a pioneer in computer animation and digital fine art and created the first computer art in 1964. Csuri was recognized by Smithsonian as the father of digital art and computer animation, and as a pioneer of computer animation by the Museum of Modern Art (MoMA) and (ACM-SIGGRAPH).

Donald P. Greenberg

Donald P. Greenberg is a leading innovator in computer graphics. Greenberg has authored hundreds of articles and served as a teacher and mentor to many prominent computer graphic artists, animators, and researchers such as Robert L. Cook, Marc Levoy, and Wayne Lytle. Many of his former students have won Academy Awards for technical achievements and several have won the SIGGRAPH Achievement Award. Greenberg was the founding director of the NSF Center for Computer Graphics and Scientific Visualization.

A. Michael Noll

Noll was one of the first researchers to use a digital computer to create artistic patterns and to formalize the use of random processes in the creation of visual arts. He began creating digital computer art in 1962, making him one of the earliest digital computer artists. In 1965, Noll along with Frieder Nake and Georg Nees were the first to publicly exhibit their computer art. During April 1965, the Howard Wise Gallery exhibited Noll's computer art along with random-dot patterns by Bela Julesz.

Other pioneers

• Benoît B. Mandelbrot
• Henri Gouraud
• Bui Tuong Phong
• Pierre Bézier
• Paul de Casteljau
• Daniel J. Sandin
• Alvy Ray Smith
• Ivan Sutherland
• Steve Russell

The study of computer graphics

A modern render of the Utah teapot, an iconic model in 3D computer graphics created by Martin Newell, 1975.

The study of computer graphics is a sub-field of computer science which studies methods for digitally synthesizing and manipulating visual content. Although the term often refers to three-dimensional computer graphics, it also encompasses two-dimensional graphics and image processing.

As an academic discipline, computer graphics studies the manipulation of visual and geometric information using computational techniques. It focuses on the mathematical and computational foundations of image generation and processing rather than purely aesthetic issues. Computer graphics is often differentiated from the field of visualization, although the two fields have many similarities.

Connected studies

Connected studies include:

• Scientific visualization
• Information visualization
• Computer vision
• Image processing
• Computational Geometry
• Computational Topology
• Applied mathematics

Applications

Computer graphics portal

Computer Science portal

• Computational biology
• Computational physics
• Computer-aided design
• Computer simulation
• Digital art
• Education
• Graphic design
• Infographics
• Information visualization
• Scientific visualization
• Video Games
• Virtual reality
• Web design

References

1. ^ What is Computer Graphics?, Cornell University Program of Computer Graphics. Last updated 04/15/98.
2. ^ ISS (2002). "What are computer graphics?". Last updated: 22 Sep 2008
3. ^ ^{a b} Wayne Carlson (2003) A Critical History of Computer Graphics and Animation. The Ohio State University
4. ^ HISTORY OF COMPUTER GRAPHICS 1960-69.
5. ^ Ira Greenberg (2007). Processing: Creative Coding and Computational Art. Apress. ISBN 159059617X. http://books.google.com/books?id=WTl_7H5HUZAC&pg=PA115&dq=raster+vector+graphics+photographic&lr=&as_brr=0&ei=llOVR5LKCJL0iwGZ8-ywBw&sig=YEjfPOYSUDIf1CUbL5S5Jbzs7M8. 
6. ^ Rudolf F. Graf (1999). Modern Dictionary of Electronics. Oxford: Newnes. pp. 569. ISBN 0-7506-4331-5. http://books.google.com/books?id=o2I1JWPpdusC&pg=PA569&dq=pixel+intitle:%22Modern+Dictionary+of+Electronics%22+inauthor:graf&lr=&as_brr=0&ei=5ygASM3qHoSgiwH45-GIDA&sig=7tg-LuGdu6Njypaawi2bbkeq8pw. 
7. ^ Blythe, David. Advanced Graphics Programming Techniques Using OpenGL. Siggraph 1999. (see: Multitexture)

Further reading

• James D. Foley, Andries Van Dam, Steven K. Feiner and John F. Hughes (1995). Computer Graphics: Principles and Practice. Addison-Wesley
• Donald Hearn and M. Pauline Baker (1994). Computer Graphics. Prentice-Hall.
• Francis S. Hill (2001). Computer Graphics. Prentice Hall.
• John Lewell (1985). Computer Graphics: A Survey of Current Techniques and Applications. Van Nostrand Reinhold.
• Jeffrey J. McConnell (2006). Computer Graphics: Theory Into Practice. Jones & Bartlett Publishers.
• R. D. Parslow, R. W. Prowse, Richard Elliot Green (1969). Computer Graphics: Techniques and Applications.
• Peter Shirley and others. (2005). Fundamentals of computer graphics. A.K. Peters, Ltd.
• M. Slater, A. Steed, Y. Chrysantho (2002). Computer graphics and virtual environments: from realism to real-time. Addison-Wesley

External links

Wikimedia Commons has media related to: Computer graphics

Look up computer graphics in Wiktionary, the free dictionary.

• A Critical History of Computer Graphics and Animation
• History of Computer Graphics series of articles
• 2D effects using particle systems

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