CG 2-marks questions

1. Define Computer graphics.

Computer graphics remains one of the most existing and rapidly growing computer fields.
Computer graphics may be defined as a pictorial representation or graphical representation of objects

in a computer.

2. What is meant by scan code? 

 

When a key is pressed on the keyboard, the keyboard controller places a code carry to the key 

pressed into a part of the memory called as the keyboard buffer. This code is called as the scan code.

3. What is meant by refreshing of the screen? 

 

Some method is needed for maintaining the picture on the screen. Refreshing of screen is done 

by keeping the phosphorus glowing to redraw the picture repeatedly. (i.e.)By quickly directing the 

electronic beam back to the same points.

4. Define Random scan/Raster scan displays? 

 

Random scan is a method in which the display is made by the electronic beam which is directed 

only to the points or part of the screen where the picture is to be drawn. 

 

The Raster scan system is a scanning technique in which the electrons sweep from top to 

bottom and from left to right. The intensity is turned on or off to light and unlight the pixel. 

5. List out the merits and demerits of Penetration techniques. 

 

The merits and demerits of the Penetration techniques are as follows 

 

 It is an inexpensive technique 

 It has only four colors 

 The quality of the picture is not good when it is compared to other techniques 

 It can display color scans in monitors 

 Poor limitation etc. 

 

6. List out the merits and demerits of DVST? 

 

The merits and demerits of direct view storage tubes [DVST] are as follows: 

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 It has a flat screen 

 Refreshing of screen is not required 

 Selective or part erasing of screen is not possible 

 It has poor contrast 

 Performance is inferior to the refresh CRT. 

7. What do you mean by emissive and non-emissive displays? 

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The emissive display converts electrical energy into light energy. The plasma panels, thin film 

electro-luminescent displays are the examples. 

 

The Non emissive are optical effects to convert the sunlight or light from any other source to 

graphic form. Liquid crystal display is an example. 

 

8. What is persistence? 

 

The time it takes the emitted light from the screen to decay one tenth of its original intensity is 

called as persistence.

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9. What is resolution? 

 

The maximum number of points that can be displayed without an overlap on a CRT is called as 

resolution. 

 

10. List out the merits and demerits of Plasma panel display: 

 

 Merits 

 

 Refreshing is not required 

 Produce a very steady image free of Flicker 

 Less bulky than a CRT. 

 

 Demerits 

 

 Poor resolution of up to 60 d.p.i 

 It requires complex addressing and wiring 

 It is costlier than CRT. 

 

11. What is Aspect ratio? 

 

The ratio of vertical points to the horizontal points necessary to produce length of lines in both 

directions of the screen is called the Aspect ratio. Usually the aspect ratio is ¾. 

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12. What is meant by Addressability? 

 

The Addressability is the number of individual dots per inch (d.p.i) that can be created. If the 

address of the current dot is (x, y) then the next dot will be (x+y), (x+y+1) etc. 

13. What is a dot size? 

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Dot size may be defined as the diameter of a single dot on the devices output. Dot size is also 

called as the Spot size. 

 

14. What is interdot distance? 

 

 Interdot distance is the reciprocal of addressability. If the addressability is large, the interdot 

distance will be less. The interdot distance should be less to get smooth shapes. 

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15. What is the difference between impact and non-impact printers? 

 

Impact printer press formed character faces against an inked ribbon on to the paper. A line 

printer and dot-matrix printer are examples. 

 

Non-impact printer and plotters use Laser techniques, inkjet sprays, Xerographic process, 

electrostatic methods and electro thermal methods to get images onto the papers. 

 

Examples are: Inkjet/Laser printers. 

 

16. What are the features of Inkjet printers? 

 

 They can print 2 to 4 pages/minutes. 

 Resolution is about 360d.p.i. Therefore better print quality is achieved. 

 The operating cost is very low. The only part that requires replacement is ink cartridge. 

 4 colors cyan, yellow, magenta, black are available. 

 

17. Define pixel. 

 

 Pixel is shortened forms of picture element. Each screen point is referred to as pixel or pel. 

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18. What is frame buffer? 

 

 Picture definition is stored in a memory area called frame buffer or refresh buffer.

19. What are the advantages of laser printer? 

 

 High speed, precision and economy. 

 Cheap to maintain. 

 Quality printers. 

 Lasts for longer time. 

 Toner power is very cheap. 

 

20. What are the advantages of electrostatic plotters? 

 

 They are faster than pen plotters and very high quality printers. 

 Recent electrostatic plotters include a scan-conversion capability. 

 Color electrostatic plotters are available. They make multiple passes over the paper to 

plot color pictures. 

                                                                                                                   to be continue...........