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graphics program[′graf·iks ‚prō·grəm]
A program for the generation of images, ranging in complexity from simple line drawings to realistically shaded pictures that resemble photographs.
drawing programA graphics program used for creating illustrations. It maintains an image in vector graphics format, which allows all elements of the picture to be isolated, moved and scaled independent of the others.
Drawing programs and CAD programs are similar; however, drawing programs usually provide a large number of special effects for fancy illustrations, while CAD programs provide precise dimensioning and positioning of each graphic element in order that the objects can be transferred to other systems for engineering analysis and manufacturing. Adobe Illustrator and CorelDRAW are popular drawing programs. Contrast with paint program. See graphics and diagramming program.
|Drawing vs. Painting|
|Although more painting tools are added to drawing programs and more drawing tools are added to paint programs, their inherent structure is entirely different. Drawing programs (vector graphics) allow for the creation of objects that can be manipulated independently. Paint programs (bitmapped graphics) provide a canvas that can be covered with electronic paint.|
graphics pipelineIn 3D graphics rendering, the stages required to transform a three-dimensional image into a two-dimensional screen. The stages are responsible for processing information initially provided just as properties at the end points (vertices) or control points of the geometric primitives used to describe what is to be rendered. The typical primitives in 3D graphics are lines and triangles. The type of properties provided per vertex include x-y-z coordinates, RGB values, translucency, texture, reflectivity and other characteristics.
An Assembly Line
Graphics rendering is like a manufacturing assembly line with each stage adding something to the previous one. Within a graphics processor, all stages are working in parallel. Because of this pipeline architecture, today's graphics processing units (GPUs) perform billions of geometry calculations per second. They are increasingly designed with more memory and more stages, so that more data can be worked on at the same time.
For gamers, photorealistic rendering at full speed is the goal, and human skin and facial expressions are the most difficult. Although there are always faster adapters on the market with more memory and advanced circuitry that render 3D action more realistically, thus far, no game has fooled anyone into believing a real person is on screen, except perhaps for a few seconds.
|These are the various stages in the typical pipeline of a modern graphics processing unit (GPU). (Illustration courtesy of NVIDIA Corporation.)|
Bus interface/Front End
Interface to the system to send and receive data and commands.
Converts each vertex into a 2D screen position, and lighting may be applied to determine its color. A programmable vertex shader enables the application to perform custom transformations for effects such as warping or deformations of a shape.
This removes the parts of the image that are not visible in the 2D screen view such as the backsides of objects or areas that the application or window system covers.
Primitive Assembly, Triangle Setup
Vertices are collected and converted into triangles. Information is generated that will allow later stages to accurately generate the attributes of every pixel associated with the triangle.
The triangles are filled with pixels known as "fragments," which may or may not wind up in the frame buffer if there is no change to that pixel or if it winds up being hidden.
Removes pixels that are hidden (occluded) by other objects in the scene.
The values for each pixel that were rasterized are computed, based on color, fog, texture, etc.
This stage adds textures and final colors to the fragments. Also called a "fragment shader," a programmable pixel shader enables the application to combine a pixel's attributes, such as color, depth and position on screen, with textures in a user-defined way to generate custom shading effects.
Mathematically combine the final fragment color, its coverage and degree of transparency with the existing data stored at the associated 2D location in the frame buffer to produce the final color for the pixel to be stored at that location. Output is a depth (Z) value for the pixel.
Frame Buffer Controller
The frame buffer controller interfaces to the physical memory used to hold the actual pixel values displayed on screen. The frame buffer memory is also often used to store graphics commands, textures as well as other attributes associated with each pixel.
image editorSoftware that allows images to be edited and also converted to different graphics formats. Image editors typically deal with only bitmapped images such as GIFs, JPEGs and BMPs; however, some editors support both bitmaps and illustrations (see vector graphics). Common functions are manually cropping and resizing the image and using "filters" to adjust brightness, contrast and colors. Myriad filters are available for special effects (see image filter). Red eye removal is included in editors specialized for photos (see photo editor).
Layers Offer Essential Flexibility
A major difference between a basic image editor and a high-end editor such as Photoshop is the support of layers, which is mandatory in commercial design. Layers enable different parts of an image to be placed in separate, transparent "canvases" that can be moved over and under each other until the desired result is achieved (see layers). See paint program, photo editor and graphics.
|Applying a Filter to an Image|
|This Photoshop screen shot shows the "lens flare" filter being applied to the image on the left. The type of camera lens, amount of brightness and position of the light can be adjusted.|
|Fixing Underexposed Images|
|Available as a stand-alone program or Photoshop plug-in, PhotoFlair uses the patented Retinex algorithm, developed by Science and Technology Corporation and NASA, to correct underexposed photos without affecting the areas with good exposure. (Image courtesy of TruView Imaging Company, www.truview.com)|
|Image Editing Program|
|An image editing program that contains layers enables bitmap elements to be treated independently. They can be placed above or below each other temporarily until the desired result is achieved.|
image processing(1) Using an application to improve or alter an image. See paint program, image editor and image filter.
(2) Image processing is an umbrella term for many functions that analyze images or convert one representation of an image into another. Although certain kinds of analog processing were performed in the past, today image processing is done in the digital domain. It is used in many fields, including surveillance, medical imaging, machine vision, robotics, computer-generated imagery (CGI), videoconferencing and satellite data analysis. Image processing is a subset of digital signal processing (see DSP).
Applications that Process Images
Face, fingerprint and iris recognition are image processing applications. A digital camera and scanner convert the view captured by the lens into a digital image file such as a JPEG (see digital camera and image filter). In video playback, the compressed video data are decoded back into full image frames for viewing (see video codec). For display and printing, graphics routines convert the data into the required matrix of pixels for the monitor or dots for the printer (see render). See imaging.
|Built-In Image Processing|
|A system-on-chip (SoC) can be very comprehensive. This block diagram of Qualcomm's Snapdragon 855 mobile SoC includes image processing circuits (Spectra 380 ISP) along with all the major components required in a modern smartphone.|
paint programAn application that allows the user to simulate painting on the computer by using the mouse or a graphics tablet. The images are generated as "bitmapped graphics," which are a matrix of picture elements (pixels). Windows comes with Paint, an elementary paint program, and image editors such as Photoshop provide a basic set of painting tools. However, the foremost paint program is Corel's Painter, which provides an unbelievable number of features (see Painter).
An Artist's Canvas
Bitmapped images are much like an artist's canvas, as all the elements in the scene are "painted" together. Colors can be changed and parts or all of an image can be run through image filters to create a wide variety of special effects. However, unlike illustrations created in a drawing program, bitmapped images cannot be resized (scaled) smaller and larger without loss of quality. See graphics, image editor and SuperPaint.
|Painting vs. Drawing|
|Although more painting tools are added to drawing programs and more drawing tools are added to paint programs, their inherent structure is different. Objects in a drawing program (vector graphics) can be resized and reshaped over and over again. Paint programs (bitmapped graphics) provide a single canvas to be covered with "electronic paint," and the only way to make changes is to paint over the existing image.|
|One of the First|
|This on-screen tool palette from SuperPaint was very sophisticated for its time. Created by Richard Shoup in the early 1970s at Xerox PARC, it was the first program to use a graphics frame buffer for "painting" an image as well as capturing and editing video. The entire system using Data General hardware took up two 5' racks (see SuperPaint). (Image courtesy of Richard Shoup.)|
|Twenty Years Later|
|The staggering increase in computing power from the 1970s to the 1990s spawned paint applications such as Painter on personal computers. These tool palettes simulate every imaginable type of brush and paper an artist could choose (see Painter).|
|Oil or Pixels?|
|Believe it or not, this "oil" was created in Painter 5 on the Macintosh by Rhoda Grossman using brush strokes with Painter's Van Gogh cloner. Named "Clo-nay, France," the impasto look (thick paint) was accomplished with Painter's Apply Surface Texture command. (Image courtesy of Rhoda Grossman, www.digitalpainting.com)|
presentation graphicsBusiness graphics, charts and diagrams used in a presentation. Presentation graphics software provides predefined backgrounds and sample page layouts to assist in the creation of computer-driven slide shows, which, in combination with a data projector, made the 35mm slide presentation obsolete. Navigation from page to page (slide to slide) can be done manually or automatically every so many seconds. The most popular presentation software is Microsoft PowerPoint (see PowerPoint).
Frames and Transitions
The format is a series of horizontal frames (slides) with transitions between them. Images, text, audio and video are laid out on the frames, and speaker's notes can be added. Like any page layout program, elements on a frame can be moved around and resized.
|Thumbnails of the slides ride in a separate window, allowing you to select and resequence them by clicking and dragging.|
|Be Your Own Videographer|
|In PowerPoint, making slides dissolve or fade into each other is done by simply clicking the transition you want.|