Data Representation - Storing Images and Sound Flashcards

1
Q

What is the most common type of image?

A

A bitmap

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2
Q

What are bitmap images?

A

Images made up of tiny dots called pixels

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3
Q

What colour is 0 in bitmap?

A

White

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4
Q

What colour is 1 in bitmap?

A

Black

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5
Q

How many bits represent each pixel in a black and white photo?

A

1 bit as there are only two colours

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6
Q

How many colours are in 2-bit images?

A

4 colours

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7
Q

What are the colours and their respective binary values in 2-bit images?

A

00 = white
01 = light grey
10 = dark grey
11 = black

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8
Q

What is colour depth?

A

The number of bits used per pixel

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9
Q

How do you work out the total amount of colours with colour depth?

A

Total amount of colours = 2 to the power of bits per pixel (1-bit image = 2 to the power of 1)

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10
Q

What colour depth do most devices?

A

24-bit colour depth

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11
Q

What is image size?

A

The number of pixel in an image (width x height)

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12
Q

What does more pixel mean for the image?

A

The image will have a higher quality

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13
Q

How do you work out file size in bits?

A

Image size (length x width) x colour depth

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14
Q

How is sound recorded by a microphone?

A

As an analogue signal

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15
Q

What are analogue signals?

A

Pieces of continually changing data

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16
Q

What does an analogue to digital converter do?

A

Converts analogue signals into digital data that computers can read and store

17
Q

What is sampling?

A

The process of converting an analogue signal to digital data

18
Q

How do you convert analogue recording to digital data?

A

Sample the amplitude of the wave at regular intervals - amplitude can only take values depending on the sample resolution

19
Q

Why is digital data different to an analogue wave?

A

Digital data isn’t continuous so it loses a lot of data

20
Q

What is the sample rate?

A

The amount of samples taken per second

21
Q

What is sample rate measured in?

A

Hertz (Hz)

22
Q

How many Hertz are in 1 kilohertz?

A

1000 Hertz

23
Q

What is sample resolution?

A

The number of bits available for each sample

24
Q

What is the bit rate?

A

Sample rate (Hz) x sample resolution (bits)

25
What is the formula for file size?
Sample rate (Hz) x sample resolution (bits) x length (seconds)
26
What will increasing the sample rate do?
The sound will be of better quality and will more closely match the original recording
27
What would increasing the sample resolution do?
Make the sampled sound closer to the quality of the original recording by PICKING UP QUIETER SOUNDS
28
What is the disadvantages of increasing the sample rate and sample resolution?
It will increase the file size