Data Compression - AP Computer Science Principles

1. Which compression type typically results in smaller file sizes?

   Lossy compression. Removing data allows for greater size reduction.

2. What is the primary trade-off in lossy compression?

   File size versus quality. Core decision in choosing compression settings.

3. What is data compression?

   Data compression reduces file size by encoding information more efficiently. Essential technique for managing storage and bandwidth efficiently.

4. What does 'decompression' mean?

   Restoring compressed data to its original form. Process of expanding compressed data back to original.

5. Identify a use case for lossy compression.

   Streaming audio or video where quality loss is acceptable. Real-time applications can tolerate some quality loss.

6. In which scenario is lossless compression favored?

   When data integrity is critical, such as text files. Perfect reconstruction is essential for text documents.

7. What is entropy in the context of data compression?

   Measure of randomness or disorder in data. Higher entropy means less predictable, harder to compress data.

8. Identify a file format that uses lossy compression.

   JPEG. Common image format that sacrifices quality for size.

9. Identify a benefit of smaller file sizes.

   Faster data transmission. Reduced file sizes improve network transfer speeds.

10. Which compression is reversible, lossy or lossless?

    Lossless compression. Only lossless compression preserves all original data.

11. Which type of compression is used in ZIP files?

    Lossless compression. File archives require perfect data preservation.

12. Which type of compression is used in MP3 audio files?

    Lossy compression. Audio quality reduction is acceptable for smaller files.

13. What is the primary goal of data compression?

    To reduce the size of data files. Fundamental objective of all compression algorithms.

14. What is Huffman coding?

    A lossless data compression algorithm using variable-length codes. Assigns shorter codes to more frequent characters.

15. What is the impact of compression on image quality?

    Potential loss of detail in lossy compression. Lossy algorithms remove visual details to reduce size.

16. What does the term 'compression ratio' refer to?

    Ratio of the size of the compressed file to the original file. Lower ratios indicate better compression efficiency.

17. What is run-length encoding (RLE)?

    A simple form of lossless data compression based on runs of data. Replaces repeated values with count and value pairs.

18. What is lossy compression?

    Compression that reduces file size by removing some data, losing quality. Trades data fidelity for smaller file sizes.

19. What does MPEG stand for?

    Moving Picture Experts Group. Standards organization for audio and video compression.

20. What role does redundancy play in data compression?

    Higher redundancy increases potential for compression. Repeated patterns enable more effective compression.

21. Which type of data is more compressible?

    Data with low entropy. Predictable data contains patterns for compression.

22. What is the primary challenge of data compression?

    Balancing compression efficiency with data quality. Optimizing both compression ratio and acceptable quality.

23. Identify the two main types of data compression.

    Lossy and lossless compression. These represent the fundamental approaches to data reduction.

24. Which type of data is less compressible?

    Data with high entropy. Random data lacks patterns for compression algorithms.

25. Identify a disadvantage of lossy compression.

    Loss of data quality and fidelity. Irreversible information loss reduces file quality.

26. What is a common algorithm used for lossless compression?

    The Lempel-Ziv-Welch (LZW) algorithm. Dictionary-based algorithm for efficient lossless compression.

27. What is a common algorithm used for lossy compression?

    The JPEG algorithm. Widely used for image compression with quality loss.

28. Identify a file format that uses lossless compression.

    PNG. Image format that preserves all original pixel data.

29. Identify a disadvantage of lossless compression.

    Larger file sizes compared to lossy compression. Perfect preservation requires more storage space.

30. What is a bit rate?

    Number of bits processed per second in a compressed file. Determines data transmission speed and quality.

31. What is the effect of compression on data transmission speed?

    Compression generally increases data transmission speed. Smaller files transfer faster over networks.

32. How does reducing the bit rate affect file size?

    It decreases the file size. Lower bit rates mean more compression and smaller files.

33. What is a codec?

    A device or program for encoding or decoding data streams. Software that compresses or decompresses digital media.

34. Name a factor that affects the choice of compression method.

    The importance of data fidelity. Critical consideration when selecting compression type.

35. Why is entropy important in data compression?

    Higher entropy indicates less potential for compression. Random data has high entropy and resists compression.

36. Identify a use case for lossless compression.

    Medical imaging where data integrity is crucial. Critical applications require perfect data preservation.

37. What is lossless compression?

    Compression that allows original data to be perfectly reconstructed. No information is permanently lost during compression.

38. Calculate the compression ratio: original size 200 MB, compressed size 50 MB.

    4:1. Original size divided by compressed size: $200 ÷ 50 = 4$.

39. What is the result of decompressing a lossy file?

    The file may not be identical to the original. Lossy compression causes permanent information loss.

40. What is the result of decompressing a lossless file?

    The file is identical to the original. Lossless compression preserves every bit of data.

Study these flashcards