5.4 Compression

• What is the primary goal of data compression?

  Reduce data size
• One benefit of data compression is reducing the required storage space
• Lossless compression techniques preserve all original data without any loss.
• Match the compression type with its characteristic:

  Lossless Compression ↔️ Preserves all original data

  Lossy Compression ↔️ Removes non-essential data
• Which compression technique is suitable for text documents and databases?

  Lossless Compression
• Lossless compression typically has a lower compression ratio
• Lossy compression is used for images, audio, and video where some data loss is acceptable.
• What are two common methods used in lossless compression?

  RLE and Huffman Coding
• An example of a lossy compression method is JPEG
• Steps involved in Run-Length Encoding (RLE)

  1️⃣ Identify repeated sequences

  2️⃣ Replace sequence with instance and count
• Run-Length Encoding (RLE) replaces sequences of repeated data with a single instance and a count.
• What does Huffman Coding assign to frequently occurring data?

  Shorter codes
• In RLE, the sequence "AAAAABBB" becomes "5A3B
• What is the primary advantage of Huffman Coding over RLE?

  Variable-length codes
• Huffman Coding assigns shorter codes to more frequent data, resulting in efficient compression.
• Match the lossless compression technique with its description:

  Run-Length Encoding (RLE) ↔️ Replaces repeated sequences

  Huffman Coding ↔️ Assigns variable-length codes based on frequency
• Discrete Cosine Transform (DCT) is used in JPEG
• What is the key trade-off in lossy compression?

  Compression vs. quality
• What does Huffman Coding assign shorter codes to?

  More frequent data
• In Run-Length Encoding, the sequence "AAAAABBB" becomes 5A3B
• Match the compression technique with its description:

  Run-Length Encoding (RLE) ↔️ Replaces repeated sequences

  Huffman Coding ↔️ Assigns variable-length codes based on frequency
• Lossless compression is crucial for text documents and databases to maintain data integrity.
• What is one common technique used in lossy compression for JPEG images?

  Discrete Cosine Transform (DCT)
• In lossy compression, data loss is yes
• Which compression type has a higher compression ratio: lossy or lossless?

  Lossy
• Data compression reduces storage space and improves data transfer speeds.
• Lossless compression results in no data loss.
• Steps involved in Run-Length Encoding (RLE)

  1️⃣ Identify repeated sequences

  2️⃣ Replace each sequence with a count and character
• What is an example of Huffman Coding for the text "HELLO"?

  L shortest, E next, H and O longer codes
• Lossy compression achieves higher compression ratios by eliminating less important information
• Lossy compression methods preserve all original data without any loss.

  False
• For what type of data is lossless compression typically used?

  Text documents and databases
• In lossy compression, some data is lost
• What does data compression reduce data size by eliminating?

  Redundancies
• Lossless compression preserves all original data
• Lossy compression is used for text documents and databases.

  False
• What type of data is lossy compression typically used for?

  Images, audio, and video
• Arrange the features of lossless and lossy compression based on their characteristics:

  1️⃣ Data Loss: No data lost (lossless), Some data lost (lossy)

  2️⃣ Compression Ratio: Lower (lossless), Higher (lossy)

  3️⃣ Use Cases: Text documents, databases (lossless), Images, audio, video (lossy)
• Lossless compression results in some data loss.

  False
• What is the primary difference between lossless and lossy compression in terms of compression ratio?

  Lower for lossless, higher for lossy