Graphics & Media Lab. >> Курсы >> Курс Ю.М.Баяковского 2001

Компьютерная графика
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blending : The transitioning of one line, surface or color into another smoothly without an observable joining edge.
blending function : The weights that are applied to two curves to assure continuity without an observable junction. They are usually in the form of cubic polinomials.
box filter : A method for modifying the color value of a pixel by averaging it with the color values of those pixels surrounding it. Used in anti-aliasing. 
Bresenham's algorithm : A mathematical algorithm for determining which pixels should be illuminated for the most accurate representation of straight line, given a
specified pixel resolution. 
brightness : 1: The average light intensity of an image. 2: The perceived amount of light as determined by luminance and chrominance of the source. Brightness is
based upon the perception of the human eye, which varies with frequency, so that is not proportional to physical energy emitted. 
byte : A unit of computer data consisting of eight bits. 

CCD : Charge-Coupled Device; a semiconductor device configured in shift-register arrays for sensing light. Used in some television cameras and scanners.
CD-ROM : Compact Disk Read Only Memory; an interchangeable digital storage media having data encoded optically on a disk for readback by laser in a drive that rotates the disk. The technology is similar to discs used for digital audio recording, but encoded differently.
cellular automata :  A technique for modeling of growth. Cellular automata are made up of mahematical cells in an array. Each cell changes its value or state according to some specified set of algorithms. The state of each cell is affected by the states of neighboring cells. 
CGA : Color Graphics Adapter; a graphics adapter card that interfaces the IBM PC and compatibles to a color monitor using a low-resolution (200x320) color graphics standard.
compositing : Composititing of images is combining images to create new images. The value of each pixel in the composited image is computed from the component images in some fashion. In an ovelay, the pixels of the foreground image must be given transparency values. A pixel's value in the composited image is taken from the background image unless the foreground image has a nontrasparent value at that point, in which case the value is taken from the foreground image. In a blending of two images, the resulting pixel value is a linear combination of the values of the two component pixels.

dithering :  Simulating gray tones by the use of varying patterns and sizes of background data.
dither matrix : An array of numbers, used in adjacent blocks repeated over the screen, providing the pattern for dithering. The matrix number associated with the screen coordinates is added to the pixel value before rounding.
dot : 1: A display of one pixel. 2: A circular marker of selectable size on an image.
dpi : Dots per inch. A measure of the quality and resolution of a display or printer. This is the number of horizontal or vertical dots that can be displayed or printed in a linear inch.

Gupta-Sproull algorithm : A technique for drawing antialiased lines. The algorithm draws three pixel wide lines using the Bresenham algorithm. It determines the proper pixel color by determining the perpendicular distance from the pixel center to the line center and then using a table lookup.

halftone : A graphic in which dots are used to represent continuous tones, with large, closely spaced dots representing darker areas and smaller, widely spaced dots representing lighter tones. This permits the printing processes, which cannot handle continuous tone images. A halftone can be created from a photograph by rephotographing it through a screen that breaks the picture up into dots.

Life game :  A game which provides a visual example of the use of cellular automata. The player sets up an array of cells and they then are born, grow, decay, or die according to simple rules. The continually changing cell pattern in displayed on the display screen.

morphing : The process of converting one image to another by warping the original image to some intermediate distorted shape and then warping this distorted shape back to the second image over the course of a number of animation frames.

pixel [from picture element] 1: One of individually addressable elements of an array of color or intensity data forming a digital image. 2: The smallest element on raster display for which the color or intensity may be independently set. 
point 1: A location in space, specified by coordinates. 2: In typesetting, the smallest unit of measure, equal to 1/72 of an inch.

quantization technique : A method for reducing a large number of colors to the limited number available for a particular display mode. Such techniques include uniform quantization, use of popularity algorithm, median cut, and octree quanization.

spline : A mathematically defined curve that provides a smooth path from one point to another with a shape controlled by a number of control points. See B-spline.

warping : 1: The two-dimensional mapping of an image to produce an image for display. 2: The distorting of an image to give an unusual effect. The technique used produces  the same results as if the image were on a sheet of rubber that is stretched in some areas and compressed in others. It is accomplished by remappping the pixels of the image using affine transformations that are determined by the relation of each original pixel to some established control points. Often warping is used in association with animation, with the image being slowly distorted from its original shape to the final shape over a period of time.

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