chapter 3--Data representation Flashcards

1
Q

What do you call it when the value that is computed cannot fit into the number of bits we have allocated for the answer?

A

overflow

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2
Q

WhAt are the first 256 characters of Unicode?

A

The ASCII extended charset

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3
Q

What type of encoding replaces frequently-used words with a single character?

A

keyword encoding

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4
Q

True/False. Run-length encoding is very good at compressing English text.

A

false.

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5
Q

What kind of encoding uses variable-length binary strings to represent characters?

A

Huffman encoding

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6
Q

True/False. The MP3 format discards information that cannot be heard by humans.

A

true

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7
Q

What does MP3 stand for? Also, describe the encoding process

A

MPEG-2, audio layer 3 file. Moving Picture Experts Group, an international committee that develops standards for digital audio and video compression. First, info that humans can’t hear is discarded, by comparing the file to mathematical models of of human psychoacoustics. Finally, the bit stream is compressed using a form of Huffman encoding.

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8
Q

How does the RGB model represent color?

A

Using 3 number values for red, green, and blue. 0 to 255 for each.

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9
Q

True/False. Bitmap, GIF, and JPEG are all examples of raster graphics formats.

A

true

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10
Q

How do vector graphics represent images?

A

in terms of lines and geometric shapes

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11
Q

True/False. A keyframe is used in temporal compression to represent the changes from one frame to another.

A

false. delta frame

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12
Q

What kind of data is a continuous representation of information?

A

analog

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13
Q

the representation for numbers you’ve used since grade school is called ______.

A

signed-magnitude representation

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14
Q

if the number system is other than base 10, we call the decimal point the ______

A

radix

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15
Q

_______ data is a discrete representation of information.

A

digital

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16
Q

Huffman codes are created based on the _____ of the character.

A

frequency

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17
Q

What is pulse-code modulation?

A

the way in which digital data is transmitted. it’s a square wave, that is either on or off at any given point in time, which corresponds to either a 0 or a 1.

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18
Q

The GIF format uses which technique?

A

Color indexing

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19
Q

What do we call the perception of the various frequencies of light that reach to retinas of our eyes?

A

Color

20
Q

What is the best format for photographic color images?

A

JPEG

21
Q

What are the video compression techniques?

A

Codecs, both spatial and temporal

22
Q

What is the technique in which an application supports only a certain number of specific colors, creating a palette from which to choose?

A

Color indexing

23
Q

Which format stores information on a pixel-by-pixel basis?

A

Raster graphics format

24
Q

What is the difference between HiColor and TrueColor?

A

HiColor is 16 bit, and TrueColor is 24 but

25
Q

Floating point?

A

Where the number of digits is fixed, but the radix floats

26
Q

Discuss a common way to store numbers on a computer.

A

64 bits.1 for the sign, 11 for the exponent, and 52 for the mantissa

27
Q

What does GIF stand for, and how does it handle color?

A

Graphics interchange format. 256 colors

28
Q

What does PNG stand for, and how is it different than JPEG?

A

Portable network graphics. Greater compression ratio, but cannot support video

29
Q

SVG?

A

Scalable vector graphics, uses vectors like Flash. Expressed in plain text.

30
Q

How is SVG different from Flashplayer?

A

Requires no editor, expressed in plain text

31
Q

Name some video codecs.

A

Sorenson, Cinepak, MPEG, & Real Video.

32
Q

What is the main ASCII character set called? How many bits/characters?

A

Latin-I Extended ASCII Character Set. 8 bits, 128 characters

33
Q

What are the first 32 characters in ASCII used for?

A

Carriage return, tabs, etc.

34
Q

How many bits does Unicode have?

A

16

35
Q

Name some audio data formats.

A

Wav, aU, aiff, vqf, MP3.

36
Q

What’s the most popular audio format, and why?

A

MP3. Better compression ratio

37
Q

How many bits do HiColor and TrueColor use?

A

HiColor is 5 bits for each color plus 1 for transparency. TrueColor is 8 bits for each color, total of 24. 0 to 255

38
Q

Bob Bemer–most important accomplishment, plus others.

A

Escape character. Also his work on ASCII. Also FORTRANSIT, a FORTRAN compiler.

39
Q

4 programming languages Bemer was involved with?

A

FORTRAN, COBOL CODASYL –(an early approach to database modeling and management), SIMULA–(a simulation language that had many object-oriented features)

40
Q

How many computer codes did Bemer’s survey include?

A

over 60

41
Q

What did Bemer’s use of the Escape character in ASCII allow?

A

an easy way to change what characters each key on the keyboard mapped to

42
Q

What does ASCII stand for?

A

American Standard Code for Information Interchange

43
Q

What color format does bit mapping support? How is it compressed?

A

24-bit TrueColor, although the color depth can be specified to reduce file size. It is compressed using run-length encoding

44
Q

When/who GIF? How many colors? What ideal for?

A

Compuserve, 1987. 256 colors. Ideal for line art and images with few colors.

45
Q

Discuss JPEG.

A

Humans are more sensitive to gradual changes of color/brightness than rapid ones. JPEG averages out the color hues over short distances.

46
Q

How does a digital signal regain its shape?

A

By being reclocked before the 1s get below 2.5 volts