Mr White Test 2

Question 1

How many unique characters are on a keyboard

Answer 1

98

Question 2

What is a Character set

Answer 2

A set of letters, symbols and digits that can be represented on a computer

Question 3

What are the two major character sets in use today

Answer 3

ASCII and unicode

Question 4

What does Unicode do better than ASCII

Answer 4

Stores characters in less bytes

Question 5

What does ASCII do

Answer 5

Encodes 128 characters into 7 bit binary code

Question 6

How many characters can unicode store

Answer 6

17 x 2^16

Question 7

What are storage forms of images

Answer 7

JPEG, PNG, GIF, BITMAP, TIFF, HEIC

Question 8

What are the two main types of graphics formats

Answer 8

Bitmaps and vectors

Question 9

What are bitmap images made up of

Answer 9

Pixels

Question 10

What is a pixel

Answer 10

The smallest identifiable area of an image

Question 11

What is each pixel

Answer 11

A single colour that is given a binary value that represents that colour

Question 12

What is the resolution of an image

Answer 12

The total number of pixels in an image (width x height)

Question 13

What is PPI or DPI

Answer 13

Pixel per inch / dots per inch. 72 PPI is typical resolution

Question 14

What is colour depth

Answer 14

The number of bits available to store the colour of each pixel

Question 15

How many colours can you represent with 3 bits

Answer 15

8. This is a colour depth of 3

Question 16

What are some different ways to represent colour

Answer 16

Red green blue (RGB), hue saturation value (HSV), hue saturation lightness (HSL)

Question 17

What is the standard depth of colour

Answer 17

24 bit RGB

Question 18

Example question: Mary has an image with a 2 bit colour depth that is 300 by 400 pixels. What is the representation in bytes?

Answer 18

30000 bytes

Question 19

Example question 2: 24 bit RGB image that is 50x100 pixels. Rep in bytes

Answer 19

15000 bytes

Question 20

Stuff about sound

Answer 20

High or low pressure waves, compression - high, refractions - low

Question 21

What is an analogue format in sound

Answer 21

Sound that originates in the real world. Has no exact value and varies continuously

Question 22

How can we represent sound

Answer 22

In the form of a wave

Question 23

What does discrete mean

Answer 23

Exact

Question 24

What must be done to sound in order to store it on a computer

Answer 24

It must be converted to a digital form

Question 25

What is ADC

Answer 25

Analogue to digital converter. Used to convert inputs to digital signals

Question 26

What is DAC

Answer 26

Digital to audio converter. Used to convert digital signals to outputs

Question 27

What does sample size/resolution/audio bit depth represent

Answer 27

Number of bits used for each sample

Question 28

What does bit rate represent

Answer 28

Number of bits used per second

Question 29

What does sampling frequency / sample rate represent

Answer 29

Number of samples per second

Question 30

What are samples in sound

Answer 30

Takes the exact value of a sound at regular intervals. Measured in hertz. 1Hz = 1 sample per second

Question 31

What does frequency / sample rate affect

Answer 31

The detail in the digital representation

Question 32

Greater the frequency greater the …

Answer 32

Accuracy and file size

Question 33

File size for sounds=

Answer 33

Bit depth x sampling rate x duration

Question 34

What does number of bits used to store each sample determine

Answer 34

How accurate the amplitude is

Question 35

Recording quality improves by:

Answer 35

Increasing the sample rate, how accurately we record the wave length by increasing it rate

Question 36

What does increasing sampling rate mean

Answer 36

Recording more data points

Question 37

What does metadata do

Answer 37

Can increase file size

Question 38

What is compression

Answer 38

The name given to algorithms which reduce file sizes

Question 39

What is decompression

Answer 39

The process where compressed data is restored to its original format

Question 40

What are the two types of compression

Answer 40

Lossy (JPG, MP3) and Lossless (PNG, TIFF, GIF)

Question 41

What does lossy compression do

Answer 41

Permanently remove some data (works when we have excess data we don’t need)

Question 42

What are digital artefacts

Answer 42

The small mistakes that result from lossy compression

Question 43

What does lossless compression do

Answer 43

Eliminates redundant information, often achieved by spotting patterns in the data

Question 44

What is run length encoding

Answer 44

When data is uncompressed it is restored exactly as it was in the original

Question 45

What is dictionary compression

Answer 45

Finds patterns in the original text and encodes each pattern in a dictionary

Question 46

Benefits of compression

Answer 46

Smaller file sizes = fewer packets = faster transmission time, reduces download times of video, sound and image files, images inside web pages appear faster, reduces space on disks / servers

Question 47

What is metadata

Answer 47

A set of data that describes and gives information about other data