Oxford AQA IGCSE · Computer Science (9210)

Representing images: Practice Questions

3 multiple-choice questions marked as you go, and 5 written questions with worked solutions. All on Representing images.

8 questions22 marksFree, no account

Question 1

1 mark

Which of the following statements best describes a pixel in the context of digital images?

Question 2

1 mark

A bitmap image has a width of \(20\) pixels and a height of \(30\) pixels. If the colour depth is set to \(8\) bits, what is the total file size in bytes?

Question 3

1 mark

An image is represented by a \(4 \times 4\) grid. The binary data for the image is 1010010110100101, where \(1\) represents black and \(0\) represents white. Which visual pattern does this create when displayed?

Question 4

2 marks

Define the term pixel and state what the word is short for.

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Question 5

3 marks

Describe how the resolution (number of pixels) and colour depth of a bitmap image collectively affect its total file size.

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Question 6

5 marks

A 4x4 bitmap uses 1-bit color depth (where 1 is black and 0 is white). If the binary data provided is 1111, 1001, 1001, 1111, describe the visual shape formed and calculate the total number of bits needed to store the pixel data.

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Question 7

4 marks

Part A: Explain what is meant by the term pixel and how pixels are used to represent a bitmap image.
Part B: A bitmap image has a resolution of \( 40 \times 30 \) pixels and uses a colour depth of 4 bits. Calculate the total file size of the image in bytes. Show your working.

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Question 8

5 marks

A digital designer is comparing two different image files.
Image A: \( 200 \times 200 \) pixels with a colour depth of 8 bits.
Image B: \( 100 \times 100 \) pixels with a colour depth of 24 bits.
Part A: Calculate the file size of Image A in kilobytes (kB).
Part B: Calculate the file size of Image B in kilobytes (kB).
Part C: Determine which image file is larger and by how many kilobytes (kB).
Note: Use 1 kB = 1,000 bytes for your calculations.

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