S.4 Computer and Information Technology
Elective C (Book 1) Revision Exercise
1. What is multimedia?
It refers to the presentation of information using a combination …
2. What is TEXT?
Text is a sequence of characters that is readable by humans.
3. Suggest four common types of text file.
DOC, TXT, PDF, HTML, RTF, DOCX
4. Among your suggestions in Q3, which format(s) contain(s) plain text?
TXT, HTML, RTF
5. Among your suggestions in Q3, which one is more suitable for sharing with others? Explain your answer.
DOC – its formatting features are preserved, moreover, it is the most common format for home user.
TXT – it can be opened by most text editors.
PDF – it is a cross platform file format, and the PDF reader is free of charge.
6. What is a font?
A font is a set of printable or displayable text characters with its style and size specified.
7. What is the height (in inch) of a 24-point font.
24*1/72 = 1/3 inch
8. State two differences between RTF and DOC formats.
Most desktop publishing software is compatible with RTF document.
RTF contains plain text only while DOC is encrypted.
9. Suggest 3 ways for inputting text into a computer.
Keyboard, Optical Character Recognition, Voice recognition, Onscreen keyboard,
Handwriting board/Digitizing Tablet

10. Suggest 3 ways to increase the accuracy of OCR.
Increase the contrast level of the source image.
Scan the document with higher resolution (dpi)./Use a large font in the source document.
The font in the document should be neat.
11. If a microsoft word 2007 document is opened by Microsoft word2003, what will happen?
DOCX cannot be opened unless a compatible software is installed.
12. If a microsoft word 2003 document is opened by Microsoft word 2007, what will happen?
DOC 2007 OK!
The file can be opened. The paragraph format/ page setting may be altered.
13. If a document is created in Microsoft Word 2007 and it is then save as a plain text file. Describe the changes to the document.
The paragraph format set in the Word 2007 will lose.
Font style, color, font size will not preserved in the plain text file.
Graphics/Chart/Table X
14. Suggest 2 characteristics of PDF file.
Password protection is allowed
The font, graphics and text layout are preserved on different platform.
15. Suggest 2 characteristics of DOC file.
The formatting code in a word document file is software-specific.
The content of a DOC file is encrypted.
The content of a DOC file is compressed.
16. Suggest 2 characteristics of TXT file.
The content of a TXT file is in plain text format.
No paragraph format/font format/page format
No formatting features.
Most word processing software can open TXT file.
17. 1 Byte = 8 bits
1 KB = 1024 B

1MB = 1024 KB
1GB = 1024MB
1TB = 1024 GB
1TB = 2^40 B
18. What is a bit?
A bit is the smallest unit of computer data.
19. Describe how a bitmap graphic stores image data.
Bitmap graphics stored as a rectangular grid of pixels and each pixel is given a color value.
20. Describe how a vector graphics stores image data.
Vector graphics are composed of lines, fills and arc.
The component objects are stored in the form of mathematical formulae.
21. Suggest two advantages of vector graphics over bitmap graphics.
The file size of vector graphics is generally smaller than bitmap graphics.
The image quality will not lose after magnifying a vector graphic.
It is easier to edit a vector graphics than bitmap graphics.
22. Suggest two advantages of bitmap graphics over vector graphics.
High-quality and photo-realistic images can be produced.
The display speed of a bitmap graphics is higher than that of vector graphics.
23. MTR company installed some public display panel on MTR platform. What should be the format of the graphics displayed on the panel (vector/bitmap)?
Explain your answer.
It uses BITMAP graphics for the display panel.
The display speed of a bitmap graphics is higher than that of vector graphics.
There is no need to magnify the graphics.
Vector graphics is not suitable for displaying complex image, such as Chinese.
24. A graphic designer is going to design and produce a company logo for XYZ company. Suggest a suitable graphics format (vector/bitmap)? Explain your answer.
He should use vector graphics.
A company logo usually consists of simple graphics.

He may need to magnify the graphics, vector graphics keep its quality after magnifying.
It is easier to edit.
25. Calculate the file size of a graphics with the follow attributes.
Resolution = 3000x4000
Color depth = true color
=3000x 4000 x 24
= 34.33MB.
26. Calculate the maximum resolution of a photo taken by a 15M pixels digital camera (4:3 aspect ratio)
Let the resolution of the photo be 4n x 3n
4n x 3n = 15,000,000
12n 2 = 15000000 n = 1118.
Therefore the resolution of the image is 4472 x 3354.
27. Describe the color model used on the Monitor/Projector.
RGB model. It presented in 3 colors (red, green, blue) in different proportion. RGB is an “additive” color model. It is a 24 bits color model.
28. Describe the color model used on printer.
Printer uses CMYK color model. Cyan, Magenta, Yellow and Black mix together to form a color. It is a “subtractive color model. It is a 32 bit color model.
29. State and describe two other types of color models of bitmap graphics.
Grey scale : 8bits (R= G= B)
Indexed color : 8 bits selected colors (stored in color table)
30. Explain with 2 reasons why digital camera stores JPG instead of BMP.
The compression ratio of JPG is greater than that of BMP.
31. Suggest a situation that using BMP is more preferable than JPG.
When the best quality is required, BMP is more preferable.
When precise editing is required, BMP is more preferable.

32. Suggest three characteristics of GIF graphics.
Support transparent background.
8 bits color depth
Lossless compression
Support animation.
*PNG support transparent background too.
*PNG support different levels (256) of transparency. (8 bits alpha channel )
33. Why TIFF is commonly used in fax software?
It is because it can store multiple images in one file.
34. Suggest four common editing features provided by graphical software.
Adjust Brightness
Rotating an image/Crop
Sharpen and Blur
Applying Filter, e.g. negative image/posterize
35. Suggest three graphics capturing devices.
Digital Camera, Scanner, webcam, Print Screen (method)
Digitizing Table/Visualizer
36. What are the common color depths of BMP graphics?
1 bit (black and White), 4 bits(16 colors), 8 bits(256 colors)
16 bits (65536 colors), 24 bits(True Color)
37. Describe the process of “sampling”.
It is a process of selecting individual audio information (sample) from an audio (population).
38. Describe the term “sample size”.
Sample size is the amount of information used to record an audio sample. (unit = bit)
39. Describe the term “sample rate/frequency”.
Sample rate is the number of samples used to record a one-second analogue audio signal.

40. What is the sample rate used for AM radio?
11025Hz.
41. What does “stereo” audio mean?
A stereo recording contains two audio channels, it offers a richer listening experience.
42. Calculate the file size of the following audio.
Sample rate = 44.1KHz
Sample Size = 16 bits
No. of Channels = stereo
Duration = 3 minutes
= 44100 x 16 x 2 x 3 x 60 bits =
43. Describe the term “bit rate”. What is it unit?
It is amount of data passing through a particular point in an audio streaming in one second. (unit = bps)
44. How does “VBR” reduce an audio file size?
VBR stands for variable bit rate. Higher bit rate can be allocated to more complicated segment of the audio stream while a lower bit rate is allocated to simpler segments, such as an interval of silence.
45. Codec = Compressor - Decompressor
46. Describe how MIDI stores audio signal.
It stores music in the form of digital musical instructions instead of a set of capture points of analogue music. (X sampling)
47. Describe how MP3 stores audio signal.
It compresses an audio by removing part of the sound signal that we cannot hear.
48. What is streaming?
Streaming technology is used to transfer data over the Internet in a continuous stream.
Portion of a media file can be played immediately while downloading.

49. Suggest three audio formats which support streaming.
RA, WMA, M4A
50. Suggest two disadvantages of using RA video format.
It requires the use of proprietary audio decompression software, RealPlayer.
Refers to any computer software that has restrictions on any combination of the usage, modification, copying or distributing modified versions of the software.
Proprietary software usually can be distributed at no cost or for a fee.
Proprietary software may also be called closed-source software.
51. Suggest two advantages of using WMA video format.
It supports lossless and lossy compression with constant or variable bit rate.
It supports by most music software and mobile music players.
52. Suggest three editing features of audio editing software.
53. What is video?
54. Calculate the file size of the following (uncompressed) video file.
Resolution = 1024x768
Color depth = 24 bits
Frame Rate = 25fps
Duration = 60 minutes
55. If the bit rate is 1150kbps, what is the file size of the above video?
56. What does PAL stand for?
57. What does NTSC stand for?
58. What does SECAM stand for?
59. Suggest three codecs supported by AVI.
60. What is the standard resolution of MPEG1 (VCD)?
61. What is the maximum resolution of MPEG2(DVD)?

62. Suggest two MPEG4 based codecs.
63. Suggest two disadvantages of RV/RM/RMVB.
64. Suggest three video format which support streaming.
65. What is streaming?
66. Suggest three editing features of video editing software.
67. What is animation?
68. Suggest two advantages of Flash movie over animated GIF.
69. Suggest a disadvantage of Flash movie .
70. What is keyframe?
71. What is tweened animation?
LONG QUESTION
Question 1
Peter is studying overseas. In the coming Christmas, he plans to create an electronic
Christmas card for his family living in Hong Kong.
(a) State two benefits to Peter for using electronic card over postal mail.
Shorter delivery time, save cost
He has two ideas for creating the electronic card.
1.
To sing a Christmas song in front of a video camera.
2.
Create an animated graphic which contains his recent photos and greeting message.
(b) For method 1, suggest two post-process after taking the video by video camera.
First, it needs to be imported into computer through USB cable.
Second, it needs to be edited.

Third, export to other file types.
(c) If the video is to be played by a traditional CRT TV, suggest a suitable video resolution.
352x288(VCD) / 720X576(DVD)
(d) How can Peter give the video to his family? Describe the process and suggest a suitable video format to archive this.
Upload the video to youtube(Online video platform)
1.
Register an account.
2.
Export the video into a suitable format.(e.g. FLV, MPEG)
3.
Upload the video file.
(e) Suggest two disadvantages of using method 1 over method 2.
1.
The file size of the video could be larger than that of the audio, it takes more time to download from the Internet.
2.
(f) For method 2, what animated graphic format should he choose? State three reasons to support your answer.
(insert)
FLV
1.
It supports 24 bits colours
2.
File size of FLV is much smaller than GIF.
3.
It supports sound effect.
4.
Support different level of transparency.
5.
Its frame rate is higher.
(g) Suggest two ways for Peter to give his animated electronic graphic to his family.
Upload to his personal web site
Send email.