Estimate an Uncompressed Representation

Supplied materials

• Paper and pencil; answers may also be spoken or typed.
• All cases, labels, numbers and rules are supplied on this page. No real account, private information or purchase is needed.

Learn the idea

A simple storage model states how many bytes represent each element. Multiplying element count by bytes per element estimates the represented data, while real files may also have headers or compression. Do not mix bits and bytes: eight bits make one byte. Our exercises state bytes directly.

Multiply recorded element count by the stated bytes per element, using consistent units. An uncompressed classroom estimate is not an exact real file size.

Use this supplied case: The model stores 8 pixels at 1 bytes per pixel, with no other data. How many bytes? Use the details in this example. Say which detail helped you choose. This pretend example does not tell us how every real system works.

1. Follow the worked example one step at a time. Say or draw what happens.
2. Multiply recorded element count by the stated bytes per element, using consistent units.
3. Say which detail makes the example answer fit. Pick another answer and say why it does not fit.
4. Try the question and practice questions. Read the rule again if your answer does not match the explanation.

Check your reasoning

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Take it further

New model:18 pixels at 3 bytes each, no overhead. Expected:54 bytes. If metadata adds 7 bytes, total 61 bytes under the revised model.

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