Multimedia Data Compression: Lempel-Ziv Encoding
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Questions and Answers

What is the basic idea behind Lempel Ziv Encoding?

  • Using a cryptographic key to encrypt strings for secure communication.
  • Encoding data using lossy compression techniques.
  • Creating a dictionary of strings for communication and substituting previously-encountered strings with their index in the dictionary. (correct)
  • Creating a table of symbols for efficient data transmission.

    • Who developed the Lempel–Ziv–Welch (LZW) universal lossless data compression algorithm?

  • Alan Turing and Claude Shannon
  • Bill Gates and Steve Jobs
  • Abraham Lempel, Jacob Ziv, and Terry Welch (correct)
  • Tim Berners-Lee and Vint Cerf

    • What is the purpose of building an indexed dictionary in the Lempel Ziv Compression algorithm?

  • To ensure the security of the compressed data.
  • To enable lossy compression of the data.
  • To create a visual representation of the compressed data.
  • To facilitate substitution of previously-encountered strings with their index in the dictionary during compression. (correct)

    • Which phase of Lempel Ziv Compression involves extracting the smallest substring that cannot be found in the remaining uncompressed string?

    <p>Compressing a string of symbols</p> Signup and view all the answers

    Which widely used file compression utility was based on the Lempel–Ziv–Welch (LZW) algorithm?

    <p>Unix file compression utility compress</p> Signup and view all the answers

    In what year was the Lempel–Ziv–Welch (LZW) algorithm published?

    <p>1984</p> Signup and view all the answers

    What is the basic idea behind Lempel Ziv Compression?

    <p>Storing the substring in a dictionary and assigning it an index value</p> Signup and view all the answers

    What is the inverse process of Lempel Ziv Compression?

    <p>Lempel Ziv Decompression</p> Signup and view all the answers

    Which statement is true about universal coding schemes like LZW?

    <p>They do not require advance knowledge about the data</p> Signup and view all the answers

    What happens in the LZW encoding algorithm when P + C is already in the dictionary table?

    <p>P is updated to P + C</p> Signup and view all the answers

    In the LZW compression example, what is added to the dictionary table after processing 'BABAABAAA'?

    <p>'BA' and 'AB'</p> Signup and view all the answers

    What is the output after processing 'BABAABAAA' using LZW compression?

    <p>'66 65 256 65 66 257 66 65 256 65 65 257 258 257 259 260'</p> Signup and view all the answers

    What does the LZW decompression process involve?

    <p>Translating each code from the compressed file through the code table to find characters it represents</p> Signup and view all the answers

    What happens if 'P + C' is not in the dictionary table in the LZW encoding algorithm?

    <p>'P + C' is added to the dictionary table</p> Signup and view all the answers

    What kind of coding scheme does LZW represent?

    <p>Universal coding scheme</p> Signup and view all the answers

    In Lempel Ziv Compression, what does 'Insert the index and the last character of the substring into the compressed string' mean?

    <p>'Index and last character are added to the end of the compressed string'</p> Signup and view all the answers

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