A computer system has many ways to communicate the processed information to the user. Computer graphics are one of the most effective and commonly used ways to communicate processed information through graphics objects such as picture charts graphs and diagrams.

In computer graphics pictures or graphics, objects are presented as a collection of discrete picture elements called pixels. The pixel is the smallest addressable skiner element. The control is achieved by setting the intensity and color of the pixel that compose the screen.

Use of computer graphics[Aims of object life]:

1. User Interface: The build graphics provided with interfaces use visual control items such as buttons, means, icons, and scrollbars. Which allows users to interact with the computer only by mouse click.
2. Plotting on graphics and charts: In industry business government and educational organizations, computer graphics are most commonly used to create mathematical, physical form histograms and tiecharts.
3. Drag and drop object: These features enable the user to create their overall design and pictures much faster by allowing them to use reading-made graphics objects or images supplied with the software.
4. Simulation and animation: The use of graphics in simulation makes mathematical models more realistic and easy to study the interactive graphics supported by animation software prove their use in the production of animated movies in Eastoon films.
5. Art and commerce: This allows users to create artistic pictures that express the message and attract attention such pictures are very useful in advertising.

Hardware requirement for graphics:

Computer graphics generally involve the following hardware devices.

• A locating device attached to a video display terminal along with drawing software is often used to directly draw a picture on a computer screen(For example mouse, Joystick).
• A rectangle-coordinated digitizer is also used as an input device for generative graphics applications for inputting drawings to a computer.
• Scanners are most commonly used as input devices for capturing photographs and drawing digital images from other things.
• Digital images are also captured by digital cameras for frame capture hardware.
• Computer screens with graphics display capability are used to display graphics.
• Laser printers are most commonly used to output graphics in hard copy form.

Software Requirement for Graphics:

The following graphics processing capabilities are highly describable in a multimedia computer system for better presentation and use of graphics information.

1. Painting or drawing software: This software allows the user to create graphics by using a mouse and various simple objects with various supporting colors.
2. Screen capture software: Screen capture software is used in such cases to capture the display of a computer screen of a graphics image.
3. Clipart: Clip art is a library of commonly used graphics images or objects. Such as personal computers, printers, flowers animals etc. We can import those pictures for other applications.
4. Graphics importing: The task of creating a multimedia application in incorporates graphics can be greatly simplified if the application software can import graphics images in some standard formal.

What are pixels?

The computer co represents only a finite number of pointers making up each line. The maximum number of distinguishable points that a line may have is a measure of the resolution of the display device. The greater the number of points, the higher the resolution. Since the lines are to be built from a finite no of points, each point must have some size so that is not a point at all. It is called a picture element or pixel.

The pixel is the smallest addressable screen element. It is the smallest piece of display screen that we can control. Each pixel has a name or address which identifies the points.

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Computer graphics images are made by setting the intensity of a string of pixels. The display screen may be assumed to be an array of pixels.

What is aspect Ratio?

The major property of a video monitor is the aspect ratio this no gives the ratio of a vertical point to the horizontal point necessary to produce an equal-length line in both directions on the screen. An aspect ratio of 3/4 means that a vertical line plotted with three-point has the same length as a horizontal line plotted with

A.R= 200_/300=V_/H

What is a frame buffer?

Or

What is a refresh buffer?

Picture definition is stored in a memory area called refresh buffer or from buffer. This memory area holds the set of intensity values for all the screen points. Store intensity values are then revealed from the reference buffer and pointed on the screen one row at a time. Each screen point is referred to as a picture element.

Raster scan display?

the most common type of graphics monitor employing a CRT is the raster scan display. In a raster sem display system, the electron beam is swapped across the screen, one row at a time, from top to bottom. As the detection beam moves across each row the beam intensity is turned on or off to create a pattern of illuminated sport.

Picture definition is stored in a memory area called a reference buffer or frame buffer. This memory area holds the set of intensity values for all the screen points. Store intercity values are then reprieved from the refresh buffer and pointed on the screen One row at a time. Each screen point is referred to as a pixel. The capability of a raster screen system to store intercity information for each screen point.

Makes it well for the realistic display. Home TV sets and printers are examples of another system that uses the raster scan method. The intensity range for pixel position depends on the capability of the system. In a simple black-white system, each screen point is either on or off. So only one bit per pixel is needed to control the intensity of the screen position. Additional bits are needed for the color system.

The architecture of the Raster scan display?

The above figure shows the architecture of a Rasrter display. It consists of a display controller center processing unit.

1. Video controller
2. Reference Buffer
3. Keyboard, mouse
4. CRT

The display images are stored in the from 1st and 0’s in the references buffer. The video controller reads this reference buffer and produces the actual image on the screen. It does this by scanning one scan line at a time from top to bottom and then back to the top.

When the beam is moved from left to right it is on the beam off when it is moved from right to left. After completion of the scanning of one line the electron beam plays back to the start of the next line and the process repeats.