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Run length encoding

Quiz by GCSE Computer Science Teacher 2

GCSE (AQA)
Computer Science
English National Curriculum

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12 questions
Show answers
  • Q1
    What is RLE (Run Length Encoding)?
    A count of the number of words in a program
    A searching algorithm
    The length of time it takes an algorithm to run
    A compression algorithm
    30s
    3.3.8.c
  • Q2
    Which of these is not an advantage of RLE?
    It is a lossless compression technique
    It can be used on multiple file types
    It can greatly reduce the size of a file if there are enough patterns or 'runs' of data
    If there are not enough patterns it can result in a larger file size
    30s
    3.3.8.c
  • Q3
    Which of these is not part of the RLE process of compressing documents?
    The letter and its number of occurrence is recorded in a pair
    Pairs are stored in a binary tree
    The occurrence of concurrent letters are recorded
    The next letter is recorded once a new letter is reached
    30s
    3.3.8.c
  • Q4
    What would the following set of letters be encoded as? 'aaabbbcccdddeefg'
    (a, b, c, d, 3) (e, 2) (f, g, 1)
    (a, 3) (b,3) (c, 3) (d, 3) (e, 2) (f, 1) (g, 1)
    (a)(b)(c)(d)3 (e)2 (f)g() 1
    (a, 3) (b,3) (c, 3) (d, 3) (e, 3) (f, 3) (g, 3)
    30s
    3.3.8.c
  • Q5
    How many bits are needed for each 'run' of data?
    16
    8
    2
    4
    30s
    3.3.8.c
  • Q6
    If the raw string 'aaabbbcccdddeeefg' uses 17 bytes, how many does the RLE version use?
    7
    17
    14
    10
    30s
    3.3.8.c
  • Q7
    How does RLE compression work on images?
    It groups together pixels of similar sizes
    It groups together all pixels of the same colour in the whole image
    It groups together pixels of the same colour that are next to each other in a run
    It looks for similar shades of colours and makes them one shade
    30s
    3.3.8.c
  • Q8
    What would the first line of this image look like after being compressed using RLE?
    Question Image
    01110
    030
    01 13 01
    02 13
    60s
    3.3.8.c
  • Q9
    What would the second line of this image look like after being compressed using RLE?
    Question Image
    11011
    212
    00100
    02 11 02
    60s
    3.3.8.c
  • Q10
    Which row of the image is encoded as O2 Y1 O2
    Question Image
    2nd
    5th
    1st
    3rd
    60s
    3.3.8.c
  • Q11
    RLE compression is able to encode which of these data types or representations?
    Pixels
    Strings of multiple characters
    Single Characters
    All of these
    60s
    3.3.8.c
  • Q12
    Why would the RLE compressed version of this use more storage than the original?
    Question Image
    There are only two colours in use
    RLE compressed images always use more space
    There are too many similar colours
    There are not enough patterns
    60s
    3.3.8.c

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