Data Representation

Question 1

equation for range of possible numbers

Answer 1

R = B^k
- where R = range, B = base, K = number of digits

Question 2

what is binary coded decimal

Answer 2

• unsigned integer
• intergeres are stored as decimal numbers
• each decimal digit is stored as its 4 - bit binary equivalent

Question 3

2 ways of representing signed integers

Answer 3

1. sign-magnitude
2. two’s complement

Question 4

what does the mantissa impact

Answer 4

range

Question 5

what does the exponent impact

Answer 5

accuracy/precision

Question 6

what is the IEEE Standard 754

Answer 6

• developed to facilitate the portability of programs
• uses BCD or DPP to represent significand (mantissa)
• signs for special values

Question 7

how is text represented

Answer 7

• represent characters as strings of bits

Question 8

what is a character set

Answer 8

a list of characters where each character in the set is enumerated
- ASCII, Unicode, UTF-8

Question 10

name the 3 types of image formats

Answer 10

1. rasters
2. HDTV
3. vector

Question 11

what is a raster and how does it represent an image

Answer 11

• aka bitmap
• each pixel is an n-bit string which encodes its colour
• rasterisation = converting a vector graphic to a raster image

Question 12

what is a HDTV and how does it represent images

Answer 12

• 1920 x 1080 pixels
• 24 bits per pixel
• total size = approx 6.2 MB

Question 13

what is vector format and hoe does it represent images

Answer 13

• image created from geometric shapes
• only need to store data for points & lines/curves between them
• smaller size than raster images
• lossless compression

Question 14

name the 3 colour models

Answer 14

1. RGB
2. HSV
3. CMYK

Question 15

what is the RGB colour model and how does it represent colour

Answer 15

• bits represent how much of each colour is needed
• expressed as a triplet of values
• # RRGGBB

Question 16

what is the HSV colour model and how does it represent colour

Answer 16

• represents colour as a cylinder
• hue = angle
• saturation = deeper colours at the edge
• value = height
• used in image & video editing software

Question 17

what is the CMYK colour model & how does it represent colour

Answer 17

• cyan, magenta & yellow
• subtracts light colours
• used in printers
• can be expressed as a tuple

Question 18

how are images captured

Answer 18

• by sampling
• no. of samples = resolution
  - expressed as pixels per inch (PPI)

Question 19

how are videos and animation captured

Answer 19

• series of still images
• image = frame
• number of frames per second defines how seamless the sequence seems
• depending on frame resolution and fps, this may require a lot of space to store