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CG_Important Question With Answer

CG_Important Question With Answer

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Published by Ashok Kumar

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Published by: Ashok Kumar on Feb 24, 2013
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Important Question with Answer
Q1. What do you mean by computer graphics?
 Ans. The branch of science and technology concerned with methods and techniques for converting datato or from visual presentation using computers.
Q2.What are the applications of computer graphics?
 Ans. 1. Computer Aided Design2. Graphical User Interface3. Entertainment4. Simulation and Training5. Education and Presentation6. Computer Generated Art7. Scientific Visualization8. Image Processing9. Virtual reality10. Cartography
Q3.What do you mean by interactive computer Graphics?
 Ans. Interactive computer Graphics like a website, it is only useful if it is browsed by a visitor and notwo visitors are exactly alike. It means the website must support the interaction of users with a variety of skills, interests and end goals. Interactive computer graphics involves the user’s interaction.
Q4. What do you mean by GUI?
 Ans. GUI stands for Graphical user interface. A major component of a GUI is a window manager thatallows a user to display multiple-window areas. To make a particular window active we simply click inthat window using an interactive pointing device. Interfaces also display menus and icons for fastselection of processing options or parameter values.
Q5. What does it mean by RGB?
 Ans. The RGB is a color model, it is an additive color model in which red, green, and blue light areadded together in various ways to reproduce a broad array of colors. The name of the model comes fromthe initials of the three additive primary colors, red, green, and blue. The main purpose of the RGB colormodel is for the sensing, representation, and display of images in electronic systems, such as televisionsand computers, though it has also been used in conventional photography.
Q6. Define VDU?
 Ans. A monitor or display (sometimes called a visual display unit) is a piece of electrical equipmentwhich displays images generated by devices such as computers, without producing a permanent record.The monitor comprises the display device, circuitry, and an enclosure. The display device inmodern monitors is typically a thin film transistor liquid crystal display (TFT-LCD), while oldermonitors use a cathode ray tube (CRT).
Q7. Define persistence in terms of CRT Phosphorous.
 Persistence is the one of the major property of phosphorous used in CRT’s. It means how long theycontinue to emit light after the electron beam is removed.Q8. Define resolution.The maximum number of points that can be displayed without overlap on a CRT is referred to as theresolution.
Q8. What do you mean by an aspect ratio?
 Aspect ratio is a number which gives the ratio of vertical points to horizontal points necessary toproduce equal length lines in both directions on the screen. An aspect ratio of ¾ means that a verticalline plotted with three points has same length as a horizontal line plotted with 4 points.
Q9.What are the different properties of phosphorus?
 1. Color2. Persistence
Q10. Differentiate raster and random scan displays.
 Ans. In a raster scan displays the electron beam is swept across the screen, one row at a time from top tobottom. Contrasting in random scan displays the electron beam is directed to the parts of the screenwhere a picture is to be drawn.
Q11.Define refresh buffer/Frame buffer?
 Picture definition is stored in a memory area called the refresh buffer or frame buffer. This memory areaholds the set of intensity values for all the screen points.
Q12. Define Pixel.
 Ans. Each screen point is referred to as a pixel or pel.
Q13. Define bitmap.
 Ans. On a black and white system with one bit per pixel, the frame buffer is commonly known as abitmap.
Q14. What do you mean by retracing? Define horizontal as well as vertical retracing.
 Ans. At the end of each scan line, the electron beam returns to the left side of the screen to begindisplaying the next scan line. The return to the left of the screen, after refreshing each scan line is calledthe horizontal retrace. And at the end of each frame, the electron beam returns to the top left corner of the screen to begin the next frame is called the vertical retrace.
Q15.What do you mean by interlacing?
 Ans. It is the method of incrementally displaying a visual on a CRT. On some raster scan systems, eachframe is displayed in two passes using an interlaced refresh procedure. In the first pass, the beam seepsacross every other scan line from top to bottom. Then after the vertical retrace, the beam sweeps out theremaining scan lines.
Q16. What is a Beam penetration method?
 Ans. This technique is used in random scan display systems. Two layers of phosphor (red and green) arecoated onto the inside of the CRT screen, the displayed colors depends on how far the electron beampenetrates into the phosphors layers. A slow electron beam excites only the outer red layer. A very fastelectron beam penetrates trough the red layer and hence excites the green layer. An average electronbeam gives the combination of red and green color. That is yellow and orange. This technique onlyprovides four colors.
Q17. Define shadow masking.
 This technique is used in raster scan display devices. It gives much wider range of colors than a beampenetration method. A shadow Mask CRT has three phosphor color dots at each pixel location. Onephosphor dot emits a red light, another emits green light and the last one emits a blue light. This type of CRT also has three electron guns one for each color dot. A shadow mask grid is installed just behind thephosphor coated screen. The three electron beams are deflected and focused as a group onto the shadowmask, which contains a series of very fine holes aligned with the phosphor dot patterns. When the threebeams pass through a hole in the shadow mask, they activate a dot triangle, which appears as a smallcolor spot on the screen .Different colors can be obtained by varying the intensity levels. More than 17

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