SLR1.2 part 2

Question 1

images are stored in…

Answer 1

binary as bitmap or vectors

Question 2

lossless compression

Answer 2

none of the data is lost, it is just encoded differently.
it can be turned back into its original format
can be used on all data types
not as effective at reducing file size compared to lossy compression
most suitable for documents and executable files

Question 3

compression

Answer 3

reduces the number of bits in a file
this reduces the storage of the file lower
makes transferring of files faster
more data can be stored on a storage device

Question 4

lossy compression

Answer 4

loses some of the data and cannot be recovered
greatly reduces the storage size
reduces the quality of images/sound
suitable for images, sound, video
not suitable for documents and executable files as some of the text would be lost

Question 5

character set

Answer 5

a defined list of characters recognised by the computer. Each characters represented by unique binary number

Question 6

examples of character sets

Answer 6

ASCII (7 bit characters et), extended ASCII (8 bit character set), unicode (24 bit character set)

Question 7

bitmap

Answer 7

pictures that are made from coloured squares called pixels

Question 8

vector

Answer 8

pictures that store the mathematics to draw the coloured shapes

Question 9

the number of values in 1 bit

Answer 9

2 possible values, 0 and 1

Question 10

sound is stored in binary through…

Answer 10

analog to digital conversion, where the sound is converted to binary to be stored

Question 11

sound file size

Answer 11

total number of bits in a second
calculated as number of samples per second x number of bits per sample x length of sample in seconds

Question 12

bit depth

Answer 12

the number of bits stored per sample
the higher the number of bits, the greater the quality of sound, the larger the file size

Question 13

sample rate

Answer 13

the number of samples stored per second
the higher the number of samples per second, the greater the quality of sound, the larger the file size

Question 14

metadata

Answer 14

additional data stored with the image to define its width, height, colour depth and colour palette.
e.g. the metadata of a document would be the name of the author

Question 15

the number of bits on a photograph

Answer 15

24 bit colour pallete

Question 16

calculating text file size

Answer 16

bits per character x number of characters

Question 17

calculating image file size

Answer 17

colour depth x image height x image width

Question 18

calculating sound file size

Answer 18

sample rate x duration in seconds x bit depth

Question 19

how is sampling used to make a recording

Answer 19

amplitude of wave is sampled
Converted to binary
measurements taken at a regular interval
(eg 44,000 times per second)

Question 20

sample frequency =

Answer 20

sample rate