Big Idea 2 · Topic 2.2 · Exercise 1
Compression Triage
25 minutes
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Q1 · 3 points on the handout
Lossy algorithms can usually reduce the number of bits MORE than lossless algorithms. Explain why that advantage follows directly from what each family is allowed to do with the original data.
Q2 · 3 points on the handout
A classmate zips a folder of vacation .jpg photos expecting it to halve in size, but the zip is barely smaller than the originals. Using EK DAT-1.D.3, explain the result - and what it reveals about files that have already been compressed.
Q3 · 2 points on the handout
ENRICHMENT: Run-length encoding stores each run of identical values as a count plus the value (the pixel row W W W W W W W W W W W W B B B W W W W W W W W W W W W becomes 12W 3B 12W). Is RLE lossless or lossy, and how do you know? Then describe one input that would make RLE ENLARGE a file instead of shrinking it, and connect that to EK DAT-1.D.3.
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