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Computer Science > Chapter 1 (1.1, 1.2, 1.3) Data representation > Flashcards

Chapter 1 (1.1, 1.2, 1.3) Data representation Flashcards

1
Q

What is Pixel

A

The smallest element used to make up an image on a display.

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2
Q

What is an image

A

a series of pixels that are converted to binary, which is processed by a computer

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3
Q

What is Colour depth

A

The number of bits used to represent the colours of a pixel.

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4
Q

What is Image resolution

A

The total number of pixels that make up an image.

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5
Q

File size of an image

A

Image resolution * colour depth

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6
Q

What is Sample rate

A

Number of samples taken per second

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7
Q

What is sampling resolution

A

The number of bits used to represent sound amplitude in a digital sound recording.

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8
Q

What is lossy compression

A

The file compression algorithm eliminates unnecessary data from the file. This means the original file cannot be reconstructed once it has been compressed. Eg: MP3, JPEG

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9
Q

What is bit depth

A

Number of bits used to represent the smallest unit in a sound file

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10
Q

How to calculate file size of a mono sound file

A

Sample rate * sample resolution * length of sample * number of channels

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11
Q

What are the two types of compression

A

Lossy
Lossless

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12
Q

What is a bit

A

Basic computing Element that is either 0 or 1.

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13
Q

What is compression

A

Reduction in file size by removing or reorganising redundant or repeated pieces of data

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14
Q

What happens when lossy compression is applied

to an img
to a sound file

A

img - reduce the resolution and/or the bit/colour depth

sound - reduce the sampling rate and/or the resolution.

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15
Q

What is lossless compression

A

A file compression method that reorganises runs of data to compress the file. The original file can be fully restored.

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16
Q

What is Run Length Encoding

A

A lossless file compression technique is used to reduce the size of text and photo files in particular

17
Q

What is an error code

A

Error messages that contain numbers that refer to the memory location of the error and are usually automatically generated by the computer

18
Q

What is ASCII code

A

A character set for all the characters on a standard keyboard and control codes.

19
Q

What is Unicode

A

A character set which represents all the languages of the world

20
Q

Applications of hexadecimals

A

MAC Address
IP Address
Representing colours
Error codes

21
Q

What is an overflow error

A

When there are more bits than the register can handle

22
Q

What directions means what operation in Binary Shifting

A

Right shift = division
Left shift = multiplication

23
Q

What is the MAC address

A

Uniquely identifies a device on the internet

24
Q

How many bits does the MAC address have?

A

48 bits - 6 pairs of hexadecimal values

25
Q

What is the IP address

A

Gives a unique address to each device connected to a network identifying their location

26
Q

IPv4

A

32 bit number
separated by ‘.’

27
Q

IPv6

A

128 bit number
separated by ‘:’
16 bit chunks (4 hex numbers:4 hex numbers)

28
Q

MP3 sound files

A

A form of lossy compression where the original file size is reduced by 90%
Lossy compression removes frequencies outside human hearing range
Perceptual music shaping

29
Q

What is perceptual music shaping

A

If two sounds are playing at the same time, the softer one is removed.

30
Q

JPEG

A

Lossy file compression.
Bitmap image which is very large becomes a JPEG file after lossy compression

Human eyes can’t detect changes in colour as well as brightness.
Separates pixel colour from brightness, images can be split into 8 x 8 pixel blocks, and allows certain information to be discarded

31
Q

MP4

A

Similar to mp3 except mp4 allows videos, photos, animations and music.

perceptual music shaping
remove repeated frames

32
Q

Why data is compressed

A

»save storage space

»reduce the time taken to stream a music or video file

»reduce the time taken to upload, download or transfer a file across a network

»reduced file size also reduces costs

33
Q

How to convert from binary to denary

A

Each value in the binary number is a power of 2

1 1 1 1
8 4 2 1

34
Q

How to convert from denary to binary

A

Subtract powers of 2 until remainder is 0

12 in binary is
12- 8 = 4 -4 = 0

1100

35
Q

How to convert binary to hexadecimal

A

take binary in groups of 4 and see what denary value they have

convert that denary value of hex

eg
1111000011111
1111 | 0000 | 1111
15 | 0 | 15
F0F

36
Q

How to convert hex to binary

A

convert each digit to groups of 4 binary digits

37
Q

Benefits of using a larger sampling resolution

A

larger dynamic range

better sound quality

less sound distortion

38
Q

how much is 1 (in bytes):

kibibyte
mebibyte
kilobyte
megabyte

A

KiB 2^10
MiB 2^20

KB 10^3
MB 10^6

Computer Science (28 decks)

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