COMPUTER GRAPHICS-UNIT-I

1.UNIT-I
2.VIDEO DISPLAY DEVICE
3.REFRESH CATHODE RAY TUBES
4.DESIGN OF CRT
5.RASTER SCAN SYSTEM
6.SIMPLE RASTER GRAPHICS SYSTEM
7.VIDEO CONTROLLER
8.BASIC VIDEO CONTROLLER
9.RANDOM SCAN SYSTEM
10.GRAPHIC MONITORS AND WORKSTATIONS
11.INPUT DEVICES
12.HARD COPY DEVICES
13.GRAPHICS SOFTWARE

1. UNIT - I Video display devices Raster scan systems Random scan systems Graphics monitors and workstations Input devices Hardcopy devices Graphics software

2. VIDEO DISPLAY DEVICES The  display devices are known as output  devices . The most commonly used output  device  in a  graphics video  monitor. The operations of most  video monitors  are based on the standard cathode-ray-tube (CRT) design. Properties of video display devices  are persistence, resolution, and aspect ratio. Computer Graphics  has become a common element in today's modern world. Be it in user interfaces, or data visualization, motion pictures etc.,  computer graphics  plays an important role. The primary output  device  in a  graphics  system is a  video monitor .

3. REFRESH CATHODE RAY TUBES A beam of  Cathode rays  discharged by an Electron gun moves through some deflection systems. So these deflection systems which direct the beam towards a described specified position on the Screen. 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. The inner side of the screen is coated with phosphor substance which gives off light when it is stroked by electrons. It is possible to control the point at which the electron beam strikes the screen, and therefore the position of the dot upon the screen, by deflecting the electron beam. 

4. DESIGN OF CRT

5. RASTER SCAN SYSTEMS A  raster scan , or  raster scanning , is the rectangular pattern of image capture and reconstruction in television. By analogy, the term is used for  raster graphics , the pattern of image storage and transmission used in most computer  bitmap image  systems . In addition to the central processing unit (CPU), a special processor, called the  video controller  or  display controller , is used to control the operation of the  display device. Simple Organization of the Video Controller  • Two registers are used to store the coordinates of the screen pixels.

6. ARCHITECTURE OF SIMPLE RASTER GRAPHICS SYSTEM

7. VIDEO CONTROLLER Display  Controller  controls the operation of the display device. It is also called a  video controller .  Working : The  video controller  in the output circuitry generates the horizontal and vertical drive signals so that the monitor can sweep. Its beam across the screen during raster scans. Architecture . In a  Raster  scan  display , the image which has to be  displayed  is saved in a binary format (0s and 1s) in the  refresh  buffer memory. Then, a video controller is used to scan each and every line of the  Refresh  Buffer Memory.

8. BASIC VIDEO CONTROLLER REFRESH OPERATIONS

9. RANDOM SCAN SYSTEMS In  Random-Scan Display  electron beam is directed only to the ares of screen where a picture has to be drawn. It is also called vector displays, as it draws picture one line at time. It can draw and refresh component lines of a picture in any specified sequence. Pen plotter is an example of random-scan displays. Random-Scan Display Processors: Input in the form of an application program is stored in the system memory along with graphics package. Graphics package translates the graphic commands in application program into a display file stored in system memory. This display file is then accessed by the display processor to refresh the screen. The display processor cycles through each command in the display file program. Sometimes the display processor in a random-scan is referred as  Display Processing Unit / Graphics Controller .

10. ARCHITECTURE OF SIMPLE RANDOM SCAN SYSTEM

11. GRAPHICS MONITORS AND WORK STATIONS Graphics monitors  can be used in personal computers  to do normal day to day task, like displaying a document or a movie or browsing internet. Graphics monitors  can be used for reverse car camera  display  systems, or CCTV camera monitoring systems. Workstations  are also used for medical imaging, simulation systems, etc. The current workstation market uses x86-64 microprocessors. Operating systems available for these platforms include  Microsoft Windows ,  FreeBSD , various  GNU / Linux distributions ,  Apple   macOS (formerly known as OS X), and  Oracle   Solaris . Some vendors also market commodity mono-socket systems as workstations.

12. A DESKTOP GENERAL-PURPOSE COMPUTER SYSTEM

13. INPUT DEVICES In computing, an input device is a piece of computer hardware equipment used .  Input devices  connected to a computer system allow the user to enter data or interact with running programs, and are used for activities ranging from editing computer programs to playing videogames (q.v.). Input devices  can be separated into five classes: keyboards, locators, picks, valuators, and buttons. Following are some of the important input devices which are used in a computer − ... Keyboard; Mouse; Joy Stick; Light pen; Track Ball; Scanner; Graphic Tablet; Microphone ...

14. TYPES OF INPUT DEVICES

15. HARD COPY DEVICES Hardcopy Devices  provides a technical summary of  computer  output  hardcopy devices such as plotters,  computer  output printers, and CRT generated  hardcopy .  Important related technical areas such as papers, ribbons and inks, colour techniques, controllers, and character fonts are also covered. An  output device  is any piece of  computer  hardware equipment which converts information into human-readable form.

16. TYPE OF OUTPUT DEVICES

17. GRAPHICS SOFTWARE In computer graphics, graphics software refers to a program or collection of programs that enable a person to manipulate images or models visually on a computer.  T here are  animation  and  video editing  software. Different types of software are often designed to edit different types of graphics such as video, photos, and vector-based drawings. The exact sources of graphics may vary for different tasks, but most can read and write files. Coordinates are always specified relative to an ordered basis. Bases and their associated coordinate representations let one realize  vector spaces and  linear transformations  concretely as  column vectors ,  row vectors , and  matrices , hence are useful in calculations.

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