AP Computer Science Principles Flashcards: Data Compression

What this deck covers

This deck focuses on Data Compression, giving you a quick way to review the definitions, rules, and examples that matter most for AP Computer Science Principles.

How to use these flashcards

Work through these flashcards in short sessions. Try to answer each prompt before flipping the card, then revisit any cards you miss until the explanation feels automatic.

Flashcard 1: Which compression is reversible, lossy or lossless?

Answer: Lossless compression. Only lossless compression preserves all original data.

Flashcard 2: What is lossless compression?

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

Flashcard 3: Identify the two main types of data compression.

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

Flashcard 4: How does reducing the bit rate affect file size?

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

Flashcard 5: What is a bit rate?

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

Flashcard 6: What is Huffman coding?

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

Flashcard 7: What is run-length encoding (RLE)?

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

Flashcard 8: Identify a disadvantage of lossless compression.

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

Flashcard 9: Identify a disadvantage of lossy compression.

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

Flashcard 10: Why is entropy important in data compression?

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

Flashcard 11: What does MPEG stand for?

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

Flashcard 12: What is entropy in the context of data compression?

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

Flashcard 13: Which compression type typically results in smaller file sizes?

Answer: Lossy compression. Removing data allows for greater size reduction.

Flashcard 14: Calculate the compression ratio: original size 200 MB, compressed size 50 MB.

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

Flashcard 15: What is data compression?

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

Flashcard 16: What does the term 'compression ratio' refer to?

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

Flashcard 17: What is a common algorithm used for lossy compression?

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

Flashcard 18: In which scenario is lossless compression favored?

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

Flashcard 19: What is a common algorithm used for lossless compression?

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

Flashcard 20: Which type of compression is used in ZIP files?

Answer: Lossless compression. File archives require perfect data preservation.

Flashcard 21: Identify a benefit of smaller file sizes.

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

Flashcard 22: Identify a use case for lossless compression.

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

Flashcard 23: Which type of data is more compressible?

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

Flashcard 24: What is the effect of compression on data transmission speed?

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

Flashcard 25: What does 'decompression' mean?

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

Flashcard 26: What is the primary challenge of data compression?

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

Flashcard 27: Which type of data is less compressible?

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

Flashcard 28: What role does redundancy play in data compression?

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

Flashcard 29: What is a codec?

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

Flashcard 30: What is the result of decompressing a lossless file?

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