by Dinesh Thakur

An EXPANSION CARD that enables a personal computer to create a graphical display. The term harks back to the original 1981 IBMPC which could display only text, and required such an optional extra card to 'adapt' it to display graphics.



 
by Dinesh Thakur

Pictures on a computer display or the process of creating pictures on a computer display. The term came into use when there was still a distinction between computers that could display only text and those that could also display pictures. This distinction is lost now that almost all computers employ a GRAPHICAL USER INTERFACE.



 
by Dinesh Thakur

A class of techniques for shrinking the size of a data file to reduce its storage requirement, by processing the data it contains using some suitably reversible algorithm. Compression methods tend to be more effective for a particular kind of data, so that text files will typically be compressed using a different algorithm from graphics or sound files.

 
by Dinesh Thakur

Also known as vector graphics, object-oriented graphics are shapes represented with mathematical formulas. (This is very different from bitmapped graphics, in which the image is mapped to the pixels on the screen, dot by dot.)

 
by Dinesh Thakur

graphical user interfaceis fondly called "GUI" pronounced "gooey." The word "graphical" means pictures; "user" means the person who uses it; "interface" means what you see on the screen and how you work with it. So a graphical user interface, then, means that you (the user) get to work with little pictures on the screen to boss the computer around, rather than type in lines of codes and commands.



 
by Dinesh Thakur

Dithering is a trick many graphic applications use to fool your eye into seeing a whole lot more colors (or grey tones) on the screen than are really there. The computer achieves this optical illusion by mixing together different colored pixels (tiny dots on the screen that make up an image) to trick the eye into thinking that a totally new color exists. For instance, since pixels are so tiny, if the computer intermingles a series of black with white dots then you're going to think you're seeing gray.



 
by Dinesh Thakur

Since large drawings cannot fit in their entirety on display screens, they can either be compressed to fit, thereby obscuring details and creating clutter, or only a portion of the total drawing can be displayed. The portion of a 2D or 3D object to be displayed is chosen through specification of a rectangular window that limits what part of the drawing can be seen.

 
by Dinesh Thakur

Built into your computer is a mapping system, or grid, complete with the ability to pinpoint any location or coordinate in the application window. This grid is laid out in the common x,y format-x being the horizontal units of measure starting from the left side of the screen, and y being the units starting from the top of the screen. It's easy to see that 0,0 would be the upper left corner of the screen. Now, if you're only using your computer for word processing, then you have no real use for knowing exactly where your cursor is. But in the painting and drawing world, knowing these coordinates is very helpful-to say the least-and it's essential in a lot of instances. Nearly all graphic and page layout applications give you a separate window which shows the coordinates of where your cursor is located at any given moment. By watching your coordinates you can move, create, shape, or select objects or portions thereof with great precision.



 
by Dinesh Thakur

The processing of a set of data in order to reduce its size. Compression may be performed both to reduce the amount of storage space occupied (say, to fit the data onto a single CD) and to reduce the time it takes to transmit (say, over a slow telephone line). Compressed data must be decompressed by reversing the process before it can be read or modified.

 
by Dinesh Thakur

CODEC is a shorthand way of saying "compressor/decompressor." It refers to a variety of software products that determine how a movie file, such as QuickTime, should be condensed, or compressed, to save space on the hard disk and to make the movie run faster. You might choose a different CODEC for video images than you would for still photography images. The different choices strike a different balance between picture quality and the size of the file (how many megabytes it requires to store it on the hard disk).

 
by Dinesh Thakur

The acronym CMYK (pronounced as the individual letters: CM Y K) stands for the process colors cyan, magenta, yellow, and black. These four process colors are the transparent ink colors that a commercial press uses to recreate the illusion of a full-color photograph or illustration on the printed page. If you look at any printed color image in a magazine, especially if you look at it through a magnifying glass (a "loupe"), you will see separate dots of ink in each of the four colors. These four colors, in varying intensities determined by the dot size and space around the dot, combine together to create the wide range of colors you appear to see.

 
by Dinesh Thakur

CLUT stands for color look-up table. A CWT is a software palette or set of 256 colors (it's actually a resource) that resides within the system software and most color-capable applications. On a computer with 8-bit color (those that are only capable of displaying a total of 256 colors), a CWT is a necessary reference to let the computer know which 256 colors out of the available 16.7 million colors (24-bit color) it can use at one time. If you think of all those 16.7 million colors as being a big (ok, very big) box of crayons, you can visualize a CWT as being a small box of handpicked colors that someone has handed you to work with. Many applications give you the option of choosing which 256 colors you want to work with. You often can set up your own palette for each particular file. For instance, if you were painting a picture of a man's face, a palette of 256 different flesh tones would be more useful than a palette containing 256 colors found in the range between black and burgundy. Take the time to explore your particular application and its documentation for a variable palette feature.



 
by Dinesh Thakur

CGM stands for computer graphics metafile, which is an international standard file format for graphic images. Most CGM files are vector graphics, although it is possible to store raster graphics in the CGM format. The purpose of creating a standard is to enable users of different systems and different programs to exchange the same graphic file. It is extremely difficult, though, to create a standard so strict that it can work seamlessly everywhere. A CGM file created in one program may not necessarily be read by every other program.



 
by Dinesh Thakur

A technique called double buffering permits one set of data to be used while another is collected. It is used with graphics displays, where one frame buffer holds the current screen image while another acquires the bits that will make up the next image. When it is ready, the buffers are switched, the new screen is displayed, and the process continues. 

 
by Dinesh Thakur

Bump Mapping: An extension of the technique Of TEXTURE MAPPING to create more realistic 3D images, in which an additional BITMAP (the bump map) applied to a surface contains not colour data but small displacements to be applied to the surface normal at each point. After the image is rendered, these displacements alter the angles of reflected rays in such a way as to convey the illusion of surface relief, even though the surface actually remains completely smooth.

 
by Dinesh Thakur

Bitmap: A table of digital BITS used to represent, for example, a picture or a text character, each bit in the table being interpreted as the presence or absence of a screen PIXEL or a printed dot. The principle can be illustrated by the following table, which represents the letter Z as a 6 x 6 table of bits:

 
by Dinesh Thakur

Bitmapped Display: Strictly, a display in which each PIXEL on the screen is represented by a BIT stored in VIDEO MEMORY which would limit its applicability to black-and-white images only. More frequently used, however, to describe any display in which each pixel corresponds to a byte or word in video memory, which covers all contemporary computer colour displays. The term was coined in distinction to the now-obsolete VECTOR DISPLAY, which drew lines instead of pixels.



 
by Dinesh Thakur

Bit Block Transfer (bitblt, bitblit): An operation used in computer graphics programming that moves a block of bits en masse from one location in memory to another. If these bits represent display pixels, the effect is to move part of an image from one place to another, and so bitblt is much used in graphical user interface code to display WINDOWS, ICONS and FONT characters quickly. Because this operation is used so extensively, many modern microprocessors provide special instructions to speed it up and a hardware GRAPHICS ACCELERATOR usually contains a dedicated unit called a BLITTER that performs the operation as quickly as possible.



 
by Dinesh Thakur

Bitmapped Font, Bitmap Font: A character FONT in which each individual letter form is stored as a table of PIXELS (a picture), in contrast to an OUTLINE FONT where each character is stored as a set of lines or strokes (a description of how to draw the character). Bitmapped fonts are fast and easy to RENDER onto a screen or printer - by simply copying the bits for the character - and for this reason were preferred on older computer systems (up to and including MS-DOS PCs) that used CHARACTER-BASED displays.



 
by Dinesh Thakur

A bitmap is an image or shape of any kind-a picture, a text character, a photo-that's composed of a collection of tiny individual dots. A wild landscape on your screen is a bitmapped graphic, or simply a bitmap. Remember that whatever you see on the screen is composed of tiny dots called pixels. When you make a big swipe across the screen in a paint program with your computerized "brush," all that really happens is that you turn some of those pixels on and some off. You can then edit that bitmapped swipe dot by dot; that is, you can change any of the pixels in the image. Bitmaps can be created by a scanner, which converts drawings and photographs into electronic form, or by a human artist (like you) working with a paint program.

 
by Dinesh Thakur

The positively charged ELECTRODE that attracts ELECTRONS within a current-consuming device such as an electrolytic cell, discharge tube or valve. In a current-producing BATTERY, the anode is the electrode that receives electrons internally and hence is connected to the external negative terminal.

 
by Dinesh Thakur

Analogue video: A video signal that is captured transmitted and stored as a continuously varying voltage, rather than as a stream of bits as in digital video. Up until the advent of digital TV in the late 1990S, television worked by transmitted analogue video signals, and older video tape recorders such as VHS, PAL, Betamax and Umatic all store analogue signals.

 
by Dinesh Thakur

Aspect ratiois a fancy term for "proportion," or the ratio of width to height. for example 4:3 for a computer screen. For instance, if a direction in a software manual tells you to "hold down the Shift key while you resize a graphic in order to maintain the aspect ratio," it simply means that if youdon'thold down the Shift key you will stretch the image out of proportion.



 
by Dinesh Thakur

Aliasing

Aliasing has two definitions, depending on whether you're talking about pictures or sounds.

When a diagonal line or a curved arc drawn on the screen looks as if it was made out of bricks, when it looks like stair steps instead of a slide, the effect is technically called aliasing. Most of us would say it had the jaggies. It can be ameliorated by the technique of ANTIALIASING.

 
by Dinesh Thakur

On a color monitor, each pixel has three dots arranged in a triad-red, green, and one blue dot. Each dot can deal with a maximum of 8 bits, which makes a total of 24 bits per pixel. With the possibility of combining the 256 levels of color in each of the three color dots, 24-bit color gives you the awesome potential of 16.7 million colors on your screen (256 times 3). Many of these colors differ so slightly that even the most acute observer couldn't tell the difference between them. Simply stated: 16 million colors is more than enough. (How do you get black and white if there are three colored dots? If all dots are on, the pixel is white; if all dots are off, the pixel is black.)

 
by Dinesh Thakur

On a grayscale monitor, each pixel can accept from 1 to 8 bits of data, which will show from 1 to 256 shades of gray.

If there are 2 bits per pixel, there are four possible combinations of on and off: on/on, off/off, on/off, and off/on. Each of these combinations displays a different shade of gray (including black and white).

 
by Dinesh Thakur

If an item is monochrome, that means it uses only one color on a differently colored background. In a monochrome monitor, these pixels have only one color phosphor. The picture is created with, say, black dots (or lines) against a white background. A monochrome image pixel can have two values, on (white) or off (black), and this can be represented by 1-bit as either 0 or 1. Most printers are monochrome, meaning they only print black toner on white paper.

 
by Dinesh Thakur

Data compression is the function of presentation layer in OSI reference model. Compression is often used to maximize the use of bandwidth across a network or to optimize disk space when saving data.

 
by Dinesh Thakur

All operations on computers are in terms of 0’s and 1’s and hence figures are also to be stored in terms of 0’s and 1’s. Thus a picture file, when viewed inside the memory, can be no different from other files – a string of Os and 1s. However, their treatment when they are to be displayed makes the difference. Pictures are actually formed with the help of frame-buffer display as follows



 
by Dinesh Thakur

Interactive graphics display consists of three components

 

a) A display controller

b) A digital memory or frame buffer

c) A television monitor

d) A video controller



 
by Dinesh Thakur

Unfortunately, the concept of graphics of displaying pictures is lot more complicated than what has been described so far - evaluate the points using the equations, store them in a file and use raster graphics methods or use simple line drawing algorithms.

 
by Dinesh Thakur

The following are also considered graphics applications

Paint programs: Allow you to create rough freehand drawings. The images are stored as bit maps and can easily be edited. It is a graphics program that enables you to draw pictures on the display screen which is represented as bit maps (bit-mapped graphics). In contrast, draw programs use vector graphics (object-oriented images), which scale better.

 
by Dinesh Thakur

The primary output device in a graphics system is a video monitor. The operation of most video monitors is based on the standard cathode ray tube (CRT) design.

 
by Dinesh Thakur

A frame buffer is a large, contiguous piece of computer memory. At a minimum  there is one memory bit for each pixel in the rater; this amount of memory is called a bit  plane. The picture is built up in the frame buffer one bit at a time.



 
by Dinesh Thakur

Image resolution describes the detail an image holds. The term applies equally to digital images, film images, and other types of images. Higher resolution means more image detail. Image resolution can be measured in various ways. Basically, resolution quantifies how close lines can be to each other and still be visibly resolved.

 
by Dinesh Thakur

A pixel (short for picture element, using the common abbreviation "pix" for "picture") is one of the many tiny dots that make up the representation of a picture in a computer's memory. Each such information element is not really a dot, nor a square, but an abstract sample.



 
by Dinesh Thakur

When choosing a monitor, one of the factors that the customer usually considers is the refresh rate. A high refresh rate is important in providing a clear picture and avoiding eye fatigue.

 
by Dinesh Thakur

Today there are very few aspects of our lives not affected by computers. Practically every cash or monetary transaction that takes place daily involves a computer. In many cases, the same is true of computer graphics. Whether you see them on television, in newspapers, in weather reports or while at the doctor’s surgery, computer images are all around you.



 
by Dinesh Thakur

The refresh rate is the number of times in a second that display the data it’s being given. This is distinct from the measure of from rate in that the refresh rate includes the repeated drawing of identical while trans rate measures how a video source can lead an entire frame of new data to a display.

 
by Dinesh Thakur

In Shadow Mask CRT tiny holes in a metal plate separate the colored phosphors in the layer behind the front glass of the screen. The holes are placed in a manner ensuring that electrons from each of the tube's three cathode guns reach only the appropriately-colored phosphors on the display.

 
by Dinesh Thakur

Resolution refers to the sharpness, or detail of the usual image. It’s a primary function of the monitor & it’s determined by the beam size & dot pitch. The screen is made up of a number of pixels.

 
by Dinesh Thakur

As ancient says “ a pixel is worth thousand words”, graphics is essential everywhere to understand the things, concepts, etc easily. Computer graphics is useful in almost all part of our life. In the following sections we are discussing some of the popular areas of computer graphics.



 
by Dinesh Thakur

Computer graphics is an art of drawing pictures, lines, charts, etc using computers with the help of programming. Computer graphics is made up of number of pixels. Pixel is the smallest graphical picture or unit represented on the computer screen. Basically there are two types of computer graphics namely.