section 2

Question 1

sampling

Answer 1

reads amplitude of Sounds at specific intervals
stores each reading as binary data
creates a digital approximation of sound

Question 2

bitmap images

Answer 2

image is represented by pixels
each pixel represents a single color
each color is represented by a binary digit

Question 3

character sets

Answer 3

collections of characters that a computer recognises from their binary representation

Question 4

color depth

Answer 4

the number of bits (binary digits) used to represent each pixel

Question 5

file size in bits for bitmap images

Answer 5

width x height x color depth

Question 6

sample rate

Answer 6

• sample rate (or sampling frequency) is the number of samples you take in a second
• it’s usually measured in Hertz or kilohertz
• e.g. a common sample rate is 44,100 samples per second 44,100 hertz or 44.1 kilohertz

Question 7

bit depth

Answer 7

number of binary digits available for each sample

Question 8

file size in bits for sound files

Answer 8

sample rate (in Hz) x bit depth x duration (in seconds)

Question 9

total number of colors

Answer 9

2^ color depth

Question 10

lossy e.g.

Answer 10

MP3 (audio)
AAC (audio)
JPEG (image)

Question 11

lossless e.g.

Answer 11

FLAC (audio
TIFF (image)
PNG (image

Question 12

cons of lossy compression

Answer 12

Lossy compression loses data - the file can’t be turned back into the original.

Lossy compression can’t be used on text or software files as these files need to retain all the information of the original.

Lossy files are worse quality than the original. But, this loss in quality is normally unnoticeable.

Question 13

cons of Lossless compression

Answer 13

Only a slight reduction in file size, so lossless files still take up quite a bit of space on your device. E.g. a lossless song may have a file size of around 30 MB, while the same song with lossy compression may be 5 MB.

Question 14

pros of lossy compression

Answer 14

Greatly reduced file size, meaning more files can be stored.

Lossy files take up less bandwidth so can be downloaded and streamed more quickly.

Commonly used - lots of software can read lossy files.

Question 15

pros of Lossless compression

Answer 15

Data is only removed temporarily so there is no reduction in quality the compressed file should look or sound like the original.

Lossless files can be decompressed turned back into the original.

Lossless compression can be used on text and software files.