Information Technology

Scan Converting a Point Each pixel on the graphics display does not represent a mathematical point. Instead, it means a region which theoretically can contain an infinite number of points. Scan-Converting a point involves illuminating the pixel that contains the point. Example: Display coordinates points as shown in fig would both be represented by pixel (2, 1). In general, a point p (x, y) is represented by the integer part of x & the integer part of y that is pixels [(INT (x), INT (y).

Scan Conversion Definition It is a process of representing graphics objects a collection of pixels. The graphics objects are continuous. The pixels used are discrete. Each pixel can have either on or off state. The circuitry of the video display device of the computer is capable of converting binary values (0, 1) into a pixel on and pixel off information. 0 is represented by pixel off. 1 is represented using pixel on. Using this ability graphics computer represent picture having discrete dots. Any model of graphics can be reproduced with a dense matrix of dots or points. Most human beings think graphics objects as points, lines, circles, ellipses. For generating graphical object, many algorithms have been developed. Advantage of developing algorithms for scan conversion Algorithms can generate graphics objects at a faster rate. Using algorithms memory can be used efficiently. Algorithms can develop a higher level of graphical objects. Examples of objects which can ...

Plotters Plotters are a special type of output device. It is suitable for applications: Architectural plan of the building. CAD applications like the design of mechanical components of aircraft. Many engineering applications. Advantage: It can produce high-quality output on large sheets. It is used to provide the high precision drawing. It can produce graphics of various sizes. The speed of producing output is high. Drum Plotter: It consists of a drum. Paper on which design is made is kept on the drum. The drum can rotate in both directions. Plotters comprised of one or more pen and penholders. The holders are mounted perpendicular to drum surface. The pens are kept in the holder, which can move left to the right as well as right to the left. The graph plotting program controls the movement of pen and drum. Flatbed Plotter: It is used to draw complex design and graphs, charts. The Flatbed plotter can be kept over the table. The plotter consists of pen and hold...

Output Devices It is an electromechanical device, which accepts data from a computer and translates them into form understand by users. Following are Output Devices: Printers Plotters Printers: Printer is the most important output device, which is used to print data on paper. Types of Printers: There are many types of printers which are classified on various criteria as shown in fig: 1. Impact Printers: The printers that print the characters by striking against the ribbon and onto the papers are known as Impact Printers. These Printers are of two types: Character Printers Line Printers 2. Non-Impact Printers: The printers that print the characters without striking against the ribbon and onto the papers are called Non-Impact Printers. These printers print a complete page at a time, therefore, also known as Page Printers. Page Printers are of two types: Laser Printers Inkjet Printers Dot Matrix Printers: Dot matrix has printed in the form of do...

Light Pen Light Pen (similar to the pen) is a pointing device which is used to select a displayed menu item or draw pictures on the monitor screen. It consists of a photocell and an optical system placed in a small tube. When its tip is moved over the monitor screen, and pen button is pressed, its photocell sensing element detects the screen location and sends the corresponding signals to the CPU. Uses: Light Pens can be used as input coordinate positions by providing necessary arrangements. If background color or intensity, a light pen can be used as a locator. It is used as a standard pick device with many graphics system. It can be used as stroke input devices. It can be used as valuators Digitizers: The digitizer is an operator input device, which contains a large, smooth board (the appearance is similar to the mechanical drawing board) & an electronic tracking device, which can be changed over the surface to follow existing lines. The electronic tracking dev...

Trackball It is a pointing device. It is similar to a mouse. This is mainly used in notebook or laptop computer, instead of a mouse. This is a ball which is half inserted, and by changing fingers on the ball, the pointer can be moved. Advantage: Trackball is stationary, so it does not require much space to use it. Compact Size Spaceball: It is similar to trackball, but it can move in six directions where trackball can move in two directions only. The movement is recorded by the strain gauge. Strain gauge is applied with pressure. It can be pushed and pulled in various directions. The ball has a diameter around 7.5 cm. The ball is mounted in the base using rollers. One-third of the ball is an inside box, the rest is outside. Applications: It is used for three-dimensional positioning of the object. It is used to select various functions in the field of virtual reality. It is applicable in CAD applications. Animation is also done using spaceball. It is used in the...

Input Devices The Input Devices are the hardware that is used to transfer transfers input to the computer. The data can be in the form of text, graphics, sound, and text. Output device display data from the memory of the computer. Output can be text, numeric data, line, polygon, and other objects. These Devices include: Keyboard Mouse Trackball Spaceball Joystick Light Pen Digitizer Touch Panels Voice Recognition Image Scanner Keyboard: The most commonly used input device is a keyboard. The data is entered by pressing the set of keys. All keys are labeled. A keyboard with 101 keys is called a QWERTY keyboard. The keyboard has alphabetic as well as numeric keys. Some special keys are also available. Numeric Keys: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 Alphabetic keys: a to z (lower case), A to Z (upper case) Special Control keys: Ctrl, Shift, Alt Special Symbol Keys: ; , " ? @ ~ ? : Cursor Control Keys: ↑ → ← ↓ Function Keys: F1 F2 F3....F9. Nume...