Choosing a compression format for a task

Name:

Date:

Class:

Quick Questions

Shade in the A or B circle for each question.

1. You need to save a school logo with sharp edges and flat colours so it stays crisp. Which format fits best?

A PNG (lossless)

B JPEG (lossy)

2. You are posting a holiday photo to a website and want a small file that loads fast. Which format fits best?

A PNG (lossless)

B JPEG (lossy)

3. A band wants to keep a perfect studio master copy of their song. Which format fits best?

A MP3 (lossy)

B FLAC (lossless)

4. You are streaming music on a phone with limited mobile data. Which format fits best?

A MP3 (lossy)

B FLAC (lossless)

5. True or false: Once a file is saved as a lossy format like JPEG, the removed detail can be fully restored.

A False

B True

Match the Pairs

Draw a line connecting each item on the left to its match on the right.

Left column		Right column
1PNG		AA lossy audio format that throws away sounds most people can't hear to make music files much smaller
2MP3		BUse MP4 (lossy)
3A designer must keep a school logo perfectly sharp with no quality lost, even after many edits		CA lossy format permanently throws data away, so the files could be damaged or changed. Documents need lossless compression like ZIP to keep every detail.
4A streaming app needs video that loads fast on slow mobile data, and tiny quality loss is acceptable		DSave as PNG (lossless)
5Send 20 holiday photos by email: save each as a huge lossless PNG		EA lossless image format that keeps every pixel, so it suits logos, diagrams and screenshots with sharp edges
6Back up a ZIP of your assignment files using a lossy format		FPhotos have lots of tiny colour changes, so lossless PNG files are very large. JPEG (lossy) makes them much smaller with little visible change.

Definitions

Lossless vs lossy choice

Fill in the Blanks

Complete each line of code by filling in the missing parts.

IF image is a logo THEN use ___ ENDIF

IF photo for website THEN use ____ ENDIF

IF every detail must be kept THEN use ________ compression ENDIF

purpose ← "stream a video" format ← ___

IF purpose = "archive music" THEN format ← ____ ENDIF

Spot the Error

Shade in the letter of the line that contains an error.

Question 1

A task = "website logo"

B sharp_edges = true

C format = "JPEG"

Question 2

A task = "stream a song"

B format = "FLAC"

C reason = "smaller file"

Question 3

A task = "backup tax documents"

B needs_every_byte = true

C format = "MP3"

Question 4

A task = "email a holiday photo"

B format = "PNG"

C reason = "small file is key"

Question 5

A if quality_must_be_perfect:

B use = "lossless"

C else:

D use = "lossless"

Answer Key

Choosing a compression format for a task

Section A: Quick Questions

A — PNG (lossless)

B — JPEG (lossy)

B — FLAC (lossless)

A — MP3 (lossy)

A — False

Section B: Match the Pairs

PNG → A lossless image format that keeps every pixel, so it suits logos, diagrams and screenshots with sharp edges

MP3 → A lossy audio format that throws away sounds most people can't hear to make music files much smaller

A designer must keep a school logo perfectly sharp with no quality lost, even after many edits → Save as PNG (lossless)

A streaming app needs video that loads fast on slow mobile data, and tiny quality loss is acceptable → Use MP4 (lossy)

Send 20 holiday photos by email: save each as a huge lossless PNG → Photos have lots of tiny colour changes, so lossless PNG files are very large. JPEG (lossy) makes them much smaller with little visible change.

Back up a ZIP of your assignment files using a lossy format → A lossy format permanently throws data away, so the files could be damaged or changed. Documents need lossless compression like ZIP to keep every detail.

Section C: Definitions

Lossless vs lossy choice — Pick lossless (PNG, ZIP, FLAC) when every detail must be kept. Pick lossy (JPEG, MP3, MP4) when a smaller file matters more than perfect quality.

Section D: Fill in the Blanks

IF image is a logo THEN
  use PNG
ENDIF

IF photo for website THEN
  use JPEG
ENDIF

IF every detail must be kept THEN
  use lossless compression
ENDIF

purpose ← "stream a video"
format ← MP4

IF purpose = "archive music" THEN
  format ← FLAC
ENDIF

Section E: Spot the Error

C — A logo has sharp edges and flat colours that lossy JPEG would blur. It should use a lossless format, so the line should be format = "PNG".

B — Streaming music works best with a small file, so a lossy format is the right pick. FLAC is lossless and gives bigger files. The line should be format = "MP3".

C — Documents must come back exactly as they were, so they need lossless compression. MP3 is a lossy audio format. The line should be format = "ZIP".

B — For a photo where a small file matters most, lossy JPEG is the better choice. PNG is lossless and makes photo files much bigger. The line should be format = "JPEG".

D — The else branch runs when perfect quality is not needed. In that case a smaller file matters more, so the choice is lossy. The line should be use = "lossy".