2.2 Data Compression

• Data compression is the process of reducing the size of data to save storage space or reduce
• Steps in lossy compression for multimedia data

  1️⃣ Convert data to frequency domain

  2️⃣ Discard high-frequency components

  3️⃣ Encode remaining data

  4️⃣ Reconstruct data partially
• The need for data compression arises from the ever-increasing amount of digital data being generated and stored
• Match the benefit of data compression with its description:

  Reduced Storage Space ↔️ Allows more data to be stored

  Faster Transmission ↔️ Enables quicker data transfer

  Efficient Bandwidth Usage ↔️ Lowers bandwidth consumption

  Improved Application Performance ↔️ Speeds up loading times
• Steps in transform coding for lossy compression

  1️⃣ Convert data into frequency domain

  2️⃣ Discard high-frequency components

  3️⃣ Encode remaining components
• What does a video codec like H.264 achieve?

  Reduces file size
• Match the lossy compression technique with its example:

  Transform Coding ↔️ JPEG image compression

  Predictive Coding ↔️ MP3 audio compression

  Vector Quantization ↔️ H.264 video codecs
• What does Vector Quantization represent a group of similar data points with?

  A single code
• There are two main types of data compression: lossless and lossy
• Data compression is essential for applications with bandwidth or storage constraints
• Order the benefits of data compression from a user perspective:

  1️⃣ Reduced Storage Space

  2️⃣ Faster Transmission

  3️⃣ Efficient Bandwidth Usage

  4️⃣ Improved Application Performance
• Run-Length Encoding is effective for data with long repeating sequences.


  True
• Which compression type permanently loses some data during compression?

  Lossy
• Data compression is essential for applications with bandwidth or storage constraints.


  True
• Which lossless compression technique assigns shorter codes to more frequent symbols?

  Huffman Coding
• Predictive Coding encodes only the difference between the current and predicted values
• Lossy compression techniques permanently discard some data to achieve greater file size reduction.

  True
• Predictive Coding in MP3 compression encodes only the difference between current and predicted values.

  True
• What is the primary goal of data compression?

  Reduce file size
• Match the compression type with its example:

  Lossless ↔️ ZIP files

  Lossy ↔️ JPEG images
• Decreased file sizes enable faster transmission over networks.


  True
• Run-Length Encoding (RLE) replaces repeating sequences with the count of the repetition
• Lempel-Ziv Welch (LZW) builds a codebook of frequently occurring phrases
• Predictive Coding reduces file size in MP3 audio compression but may degrade audio quality.


  True
• Lossless compression allows the original data to be perfectly reconstructed, while lossy compression permanently discards some data.


  True
• What are the two main categories of data compression techniques?

  Lossless and lossy
• What is the key difference between lossless and lossy compression in terms of data fidelity?

  Data fidelity is preserved in lossless compression
• The Lempel-Ziv Welch (LZW) algorithm builds a codebook of frequently occurring phrases
• Lossless compression is preferred for applications where data fidelity must be preserved.


  True
• Match the lossy compression technique with its description:

  Transform Coding ↔️ Discards high-frequency components

  Predictive Coding ↔️ Encodes differences between values

  Vector Quantization ↔️ Represents data with a single code
• Vector Quantization in video codecs like H.264 can introduce blurriness or blockiness
• The MP3 audio compression encodes only the difference between the current and predicted values
• Lossless compression provides higher compression ratios compared to lossy compression.

  False
• Run-Length Encoding (RLE) replaces repeating sequences with a count of the repetition.


  True
• What type of data is commonly compressed using transform coding, and what is a potential drawback?

  Images; visual artifacts
• In lossless compression, the original data can be perfectly reconstructed from the compressed data.


  True
• Lossless compression reduces file size by removing redundant data.


  True
• What is an example of a file format commonly associated with lossless compression?

  ZIP
• Run-Length Encoding (RLE) replaces repeating sequences with the count of the repetition
• Lossy compression always results in reduced data quality compared to the original.


  True