COMPUTER GRAPHICS –IMPORTANT QUESTIONS
All Units
Computer graphics
Two Marks:
1.Define computer graphics and list out the types of computer graphics.
2.Write the important applications of computer graphics.
3.Differentiate between Raster and Vector graphics.
4.Differentiate between bitmap and pixmap.
5.Give any three components for generating the basic transformation matrix.
6.What is clipping and clip window.
7.Define window and viewport.
8.What is rotation?
9.Differentiate perspective and parallel projection.
10.Name any two three dimensional graphics package procedures related with suitable visible surface
detection.
11.List out the any four input devices.
12.Define (i) aspect ratio
(ii) Persistence
(iii) Resolution
13.What is called inkjet printers?
14.Define plotters.
15.What is meant by refresh buffer and frame buffer?
16.Define window port and view port.
17.What is meant by clipping? What are all the types of clipping?
18.Define scaling.
19.What is meant by line attributes?
20.Define rotation.
21.What do you mean by emissive and non-emissive displays?
22.What is the difference between impact and non-impact printers?
23.What do you mean by ‘jaggies’?
24.What is scan line algorithm?
25.What is a Line cap?
26.What is antialiasing?
27.What is Transformation?
28.What is translation?
29.What is scaling?
30.What is shearing?
31.What is reflection?
32.List out the various Text clipping?
33.What are the steps involved in 3D transformation?
34.What do you mean by view plane?
35.What is view distance?
36.What is Projection reference point?
37.What are the different types of parallel projections?
38.What is orthographic parallel projection?
39.What is orthographic oblique projection?
40.What is view reference point?
FiveMarks:
1.Write short notes on raster scan displays and neat diagram.
2.Explain the application ofcomputer graphics.
3.Explain in detail about DDAline algorithm.
4.Write short note s on graphics software standard.
5.Write short notes on color and grayscale level.
6.Explain in detail about 2DBasic transformations and Other transformations.
7.Explain in detail Cohen Sutherland algorithm.
8.Explain about Bresenham’s line drawing algorithm.
9.Explain the attributes of line style.
10.Write a note on window-to-view port devices.
11.Briefly discuss about logically classification of input devices.
12.Describe about various three dimensional display methods.
13.Explain in detail about 3D viewing transformation.
14.Explain the concept of hidden line removal
.
Ten Marks:
1.Explain in detail about video display devices with neat diagram.
2.Write about the applications of Computer Graphics.
3.Difference between Raster scan display and random scan display.
4.Explain in detail about color CRT monitors.
5.Explain in detail about clipping algorithms.
6.Discuss in detail about circle generating algorithms.
7.Discuss the general procedures for applying two dimensional basic transformations.
8.Discuss detail about Cohen Sutherland line clipping algorithm.
9.Explain about basic three dimensional Transformations in detail.
10.Discuss detail about projection types in three dimensional.
11.Explain Back face detection method and Depth buffer method.
12.Explain Depth sorting method.
13.Explain A Buffer Method.
14.Explain about clipping operations.
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Question 1. What is computer graphics?
Answer- The term computer graphics include almost every thing on computer that is not text or sound. It is an art of drawing pictures, lines. charts, e.t.c using computers with the help of programming. Or we can say that graphics is the representation and manipulation of image data by computer with the help from specialized software and hardware.
Question 2. Write the important applications of computer graphic?
Answer- Following are the applications of computer graphic
1. computer graphics is used in the field of computer aided design.
2. It is used to produce illustrations for reports or to generate slide for with projections.
3. Computer graphic methods are widely used in both fine are and commercial are applications.
4. The artist uses a combination of 3D modeling packages, texture mapping, drawing programs and CAD software.
5. In the field of entertainment CG methods are now commonly used in making motion pictures. music videos and television shows.
6. Computer-generated models of physical, financial and economic systems are often used as educational aids.
Question-3 What are the raster and vector graphics?
Answer-
RASTER- In computer graphics image, or BITMAP, is a dot matrix data structure representing a generally rectangular grid of pixels or points of color, viewable via a monitor, paper, or other display medium. Raster image are stored in image files with varying formats.
VECTOR- Vector graphics is the use of geometrical primitives such as points, lines, curves, and shapes or polygon, which are all based on mathematical expressions, to represent image in computer graphics. “Vector”, in this context, implies more than a straight line.
Question-4 Write the difference between vector and raster graphics?
Answer-
1. Raster or Bitmap images are resolution dependent because of this its not possible to increase or decrease their size without sacrificing on image quality.
While vector based image are not dependent on resolution. The size of vector image image can be increased or decreased without affecting image quality.
2. Raster or bitmap images are always rectangular in shape, Vector image, however, can have any shape.
3. Unlike raster image, vector image can’t be use for realistic images. This is because vector images are made up of solid color areas and mathematical gradients, so they can’t be used to show continuous tones of a colors in a natural photograph.
Question-5 What is scaling in computer graphics?
Answer- In computer graphic, image scaling is the process of resizing a digital image. scaling is a non-trivial process that involves a trade off between efficiency, smoothness and sharpness. With bitmap graphics, as the size of an image is reduced or enlarged, the pixels which comprise the image become increasingly visible, making the image appear “soft” if pixels are averaged, or jagged if not.
Question-6 What are the hardware devices used for computer graphics?
Answer-
Input Devices
Keyboard, Mouse, Data tablet, Scanner, Light pen, Touch screen, Joystick
Output Devices
Raster Devices- CRT, LCD, LED, Plasma screens, Printers
Vector Devices- Plotters, Oscilloscopes
Question-7 What are the features of inkjet printers?
Answer- Features of inkjet printers are-
1. They can print 2 to 4 pages per minute.
2. resolution is about 360d.p.i. Therefor better print quality is achieved.
3. The operating cost is very low. The only part that requires replacement is ink cartridge.
4. Four colors cyan, yellow, magenta, black are available.
Question-8 What are the advantages of electrostatic plotters?
Answer-
1. They are faster then pen plotters and very high quality printers.
2. Recent electrostatic plotters includes a scan conversion capability.
3. color electrostatic plotters are available. They make multiple passes over the paper to plot color picture.
Question-9 What is meant by scan code?
Answer- When a key is pressed on the keyboard, the keyboard controller places a code carry to the key pressed in to the part of the memory called as the keyboard buffer. This code is called as scan code.
Question-10 Define Random and Raster scan displays?
Answer- Random scan is a method in which display is made by electronic beam, which is directed only to the points or parts of the screen where picture is to be drawn.
The Raster scan system is a scanning technique in which the electron sweep from top to bottom and from left to right. The intensity is turned on or off to light and unlighte the pixel.
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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 data to or from visual presentation using computers.
Q2.What are the applications of computer graphics?
Ans. 1. Computer Aided Design
2. Graphical User Interface
3. Entertainment
4. Simulation and Training
5. Education and Presentation
6. Computer Generated Art
7. Scientific Visualization
8. Image Processing
9. Virtual reality
10. 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 no two visitors are exactly alike. It means the websit
e 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 that allows a user to display multiple-window areas. To make a particular window active we simply click in that window using an interactive pointing device. Interfaces also display menus and icons for fast selection 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 are added together in various ways to reproduce a broad array of colors. The name of the model comes from the initials of the three additive primary colors, red, green, and blue. The main purpose of the RGB color
model is for the sensing, representation, and display of images in electronic systems, such as televisions and 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 equipment which 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 in
modern monitors is typically a thin film transistor liquid crystal display (TFT-LCD), while older monitors 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 they continue to emit light after the electron beam is r
emoved.
Q8. Define resolution.
The maximum number of points that can be displayed without overlap on a CRT is referred to as the resolution.
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 to produce equal length lines in both directions on the screen. An aspect ratio of ¾ means that a vertical line plotted with three points has same length as a horizontal line plotted with 4 points.
Q9.What are the different properties of phosphorus?
1. Color
2. 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 to bottom. Contrasting in random scan displays the ele
ctron beam is directed to the parts of the screen where 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 area holds 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 a bitmap.
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 begin displaying the next scan line. The return to the le
ft of the screen, after refreshing each scan line is called the 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, each frame is displayed in two passes using an interlace
d refresh procedure. In the first pass, the beam seeps
across every other scan line from top to bottom. Then after the vertical retrace, the beam sweeps out the remaining 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) are coated onto the inside of the CRT screen, the displ
ayed colors depends on how far the electron beam penetrates into the phosphors layers. A slow electron beam excites only the outer red layer. A very fast electron beam penetrates trough the red layer and hence excites the green layer. An average electron beam gives the combination of red and green color. That is yellow and orange. This technique only provides four colors.
Q17. Define shadow masking.
This technique is used in raster scan display devices. It gives much wider range of colors than a beam penetration method. A shadow Mask CRT has three phosphor color dots at each pixel location. One phosphor 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 the phosphor coated screen. The three electron beams ar
e deflected and focused as a group onto the shadow mask, which contains a series of very fine holes aligned with the phosphor dot patterns. When the three
beams pass through a hole in the shadow mask, they activate a dot triangle, which appears as a small color spot on the screen .Different colors can be o
btained by varying the intensity levels. More than 17million different colors can be obtained in a full color system.
Q18. What are composite monitors?
Ans. Composite monitors are the adaptations of TV sets that allow bypass of the broadcast circuitry. These display devices still require that the pictur
e information be combined, but no carrier signal is needed. Picture information is combined into a composite signal and then separated by the monitor, so
the resulting picture quality is still not the best attainable.
Q19. What are advantages of DVST over CRT? Also list some disadvantages of DVST.
Ans. Advantages:
i. No refreshing is needed.
ii. Very complex pictures can be displayed at very high resolution without flicker.
Disadvantages:
i. They ordinarily do not display color
ii. Selected part of the picture can not be erased
iii. The erasing and redrawing process can take several seconds for complex pictures.
Q20. Differentiate emissive and non emissive displays.
Ans. Emissive display displays are devices that convert electrical energy into light.Non-emissive displays use optical effects to convert sunlight or light from some other source into graphics patterns.
Q21. List some 3D viewing devices.
Ans. 1. Stereoscopic systems
2. Virtual reality systems
Q22. What is the role of a video controller?
Ans. It is the one of the component of an interactive raster scan system. It is used to control the operation of the display device by accessing the frame buffer to refresh the screen.
Q23. Define Graphics controller /Display controller
/Display processor.
Ans. The purpose of the display processor is to free the CPU from graphic chores. A major task of the display processor is digitizing a picture definition given in an application program into a set of pixel intensity values for storage in the frame buffer.
Q24. What do you mean by scan conversion?
Ans. A major task of the display processor is digitizing a picture definition given in an application program into a set of pixel intensity values for storage in the frame buffer. This digitization process is called scan conversion.
Q25. Explain the merits and demerits of Penetration
techniques.
Ans. The merits and demerits of the Penetration techniques are as follows;
[1] It is an inexpensive technique
[2] It has only four colors
[3] The quality of the picture is not good when it is compared to other techniques
[4] It can display color scans in monitors
Q26. Explain the merits and demerits of DVST.
Ans. The merits and demerits of direct view storage
tubes [DVST] are as follows;
[1] It has a flat screen
[2] Refreshing of screen is not required
[3] Selective or part erasing of screen is not possible
[4] It has poor contrast
[5] Performance is inferior to the refresh CRT.
Q27. Explain the merits and demerits of Plasma panel display.
ADVANTAGES:
[1] Refreshing is not required
[2] Produce a very steady image free of Flicker
[3] Less bulky than a CRT.
DISADVANTAGES:
[1] Poor resolution of up to 60 d.p.i
[2] It requires complex addressing and wiring
[3] It is costlier than CRT.
Q28.What is the difference between impact and non-impact printers?
Impact printers 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.
Q29. What is the features of Inkjet printers?
Features:
a] They can print 2 to 4 pages/minutes.
b] Resolution is about 360d.p.i. Therefore better print quality is achieved.
c] The operating cost is very low. The only part that requires replacement is ink cartridge.
d] 4 colors cyane, yellow, majenta, black are available.
Q30.What are the advantages of laser printers?
Ans. 1] High speed, precision and economy.
2] Cheap to maintain.
3] Quality printers.
4] Lasts for longer time.
5] Toner power is very cheap.
Q31.What is the advantages of electrostatic plotters?
1] They are faster than pen plotters and very high quality printers.
2] Recent electrostatic plotters include a scan-conversion capability.
3] Color electrostatic plotters are available. They make multiple passes over the paper to plot color pictures.
Q32.Consider three different raster systems with re
solutions of 640 x 480, 1280 x 1024, and 2560 x
2048.
a) What size is frame buffer (in bytes) for each of
these systems to store 12 bits per pixel?
Ans. Because eight bits constitute a byte, frame-bu
ffer sizes of the systems are as follows:
640 x 480 x 12 bits / 8 = 450KB;
1280 x 1024 x 12 bits / 8 = 1920KB;
2560 x 2048 x 12 bits / 8 = 7680KB;
b) How much storage (in bytes) is required for each
system if 24 bits per pixel are to be stored?
Similarly, each of the above results is just doubled for 24 (12×2) bits of storage per pixel.
Q33.Consider two raster systems with the resolutions of 640 x 480 and 1280 x 1024.
a) How many pixels could be accessed per second in each of these systems by a display controller that refreshes the screen at a rate of 60 frames per second?
Ans. Since 60 frames are refreshed per second and each frame consists of 640 x 480 pixels, the access
rate of such a system is (640 x 480) * 60 = 1.8432
x 107 pixels/second.Likewise, for the 1280 x 1024 system, the access rate is (1280 x 1024) * 60 = 7.86432 x 107pixels/second.
b) What is the access time per pixel in each system?
Ans. According to the definition of access rate, we know that the access time per pixel should be 1/(access rate). Therefore, the access time is arou
nd 54 nanoseconds/pixel for the 640 x 480 system, andthe access time is around 12.7 nanoseconds/pixel for the 1280×1024 system.
Q34. Consider a raster system with the resolution of 1024 x 768 pixels and the color palette calls for 65,536 colors. What is the minimum amount of video RAM that the computer must have tosupport the above-mentioned resolution and number of colors?
Ans. Recall that the color of each pixel on a display is represented with some number of bits. Hence,a Display capable of showing up to 256 colors is using 8 bits per pixels (i.e. “8-bit color”).Notice first that the color palette calls for 65,536 colors. This number is but 216 , which implies that 16 bits are being used to represent the color of each pixel on the display. The display’s resolution is 1024 by 768 pixels, which implies that there is a total of 786,432 (1024 × 768) pixels on the display. Hence,the total number of bits required to display any of 65,536 colors on each of the screen’s 786,432 pixels is 12,582,912 (786,432 × 16). Dividing
this value by 8 yields an answer of 1,572,864 bytes. Dividing
that value by 1,024 yields an answer of 1,536 KB. D
ividing that value by 1,024 yields an answer of 1.5MB.
Q35. Define resolution.
Ans. The maximum number of points that can be displayed without overlap on a CRT is referred to as the resolution.
CS2401 Computer Graphics Anna University Question paper Question Bank University Question bank Important Question 2 marks 16 Marks questions for all Units
QUESTION BANK
UNIT- I OUTPUT PRIMITIVES
Part-A (2-MARKS)
1. What is the purpose of presentation graphics?
2. Define refresh buffer/frame buffer.
3. What is pixel?
4. Define aspect ratio.
5. What is Output Primitive?
6. What is DDA?
7. What are the disadvantages of DDA algorithm?
8. What is attribute parameter?
9. What is the basic line attributes?
10. What is meant by aliasing?
11. Define Translation.
12. Define Rotation.
14. Define Reflection.
15. Define Shear.
16. Define Window.
17. Define view port.
18. What is viewing transformation?
19. Define Clipping.
20. What are the types of Clipping?
Part-B (16-MARKS)
1. Explain the basic concept of Midpoint ellipse algorithm. Derive the decision parameters for the algorithm and write down the algorithm steps. (16)
2. Explain two dimensional Translation and Scaling with an example. (16)
3. Obtain a transformation matrix for rotating an object about a specified pivot point. (16)
4. Explain DDA line drawing algorithm. (16)
5. Explain the steps in midpoint ellipse drawing algorithm. (16)
6. What is polygon clipping? Explain Sutherland-Hodgeman algorithm for polygon (16)
7. Explain about socket, connect, bind, listen and accept functions. (16)
8. Consider a triangle ABC whose coordinates are A[4,1], B[5,2], C[4,3]
a. Reflect the given triangle about X axis. (4)
b. Reflect the given triangle about Y-axis. (4)
c. Reflect the given triangle about Y=X axis. (4)
d. Reflect the given triangle about X axis. (4)
9. Explain Sutherland Hodgeman polygon clipping algorithm. Explain the (16)
Disadvantage of it and how to rectify this disadvantage.
10. Explain Two Dimensional Viewing. (16)
11. Explain Bresenham’s Line Drawing Algorithms.
UNIT- II THREE DIMENSIONAL CONCEPTS
Part-A (2-MARKS)
1. Categorize the 3D representations?
2. What Boundary representation?
3. What space-partitioning representation?
4. What is Blobby Object?
5. What is projection?
6. What are the types of projection?
7. What is parallel projection?
8. What is Perspective projection?
9. What is chromaticity?
10. Define Color model..
11. What are the uses of chromaticity diagram?
12. What is HSV model?
13. what for CMY color model used?
14. What are the parameters in the HLS color model?
15. Define Computer animation.
16. What are the steps in animation sequence?
17. How frame-by-frame animation works?
18. What is morphing?
19. What are the methods of motion specifications?
Part-B (16-MARKS)
1. Explain 3D basic transformation with an example. (16)
2. Design a storyboard layout and accompanying key frames for an animation (16)
3. How to specify objects motion in an animation system. (16)
4. Derive the 3D transformation matrix for rotation about
(i) an arbitrary axis (8)
(ii) an arbitrary plane (8)
5. Explain RGB, CMY, YIQ and YUV color models. (16)
6. Brief about select function and shut down functions. (16)
7. Explain the properties of B spline. How it is differ from Bezier? (16)
8. How to represent an object on 3D scene? (16)
9. Explain three dimensional geometric and modeling transformations. (16)
10. Explain three dimensional Viewing and Functions. (16)
11. Draw the CIE chromaticity diagram and explain. (16)
12. Explain different types of color model in detail. (16)
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