Oxford Cambridge and RSA
GCSE (9-1) Computer Science
Computer Systems
J277/01
Topic: Unit 1.2 Images (Bitmap)
Time allowed: 30 minutes
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Candidate number
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INSTRUCTIONS
Use black ink.
Answer all the questions.
INFORMATION
The total mark for this paper is 20.
The marks for each question are shown in brackets [ ].
Turn over
1
Images are stored on a computer as bitmaps.
(a) Define the term 'pixel'.
[1]
(b) State what is meant by 'image resolution'.
[1]
(c) Define the term 'colour depth'.
[1]
2
An image has a resolution of 100 x 100 pixels and a colour depth of 2 bits.
(a) Calculate the file size of this specific image in bits.
Show your working.
[2]
Working:
Answer: bits
(b) State the maximum number of different colours that can be represented in this image.
[1]
Answer:
3
A graphic designer creates a logo for a website.
They decide to increase the colour depth of the logo from 8-bit to 24-bit.
(a) Explain the effect this change will have on the file size of the image.
[2]
(b) Explain the effect this change will have on the quality of the image.
[2]
Turn over
4
A digital camera takes a photograph. Along with the pixel data, the file stores 'Metadata'.
(a) State two items of metadata that would be stored with the image.
[2]
1.
2.
(b) Explain why the computer needs metadata to display the image correctly.
[2]
5
A student scans a photograph into the computer.
The resulting file is 3,000,000 bytes.
Calculate the file size in Megabytes (MB). You must use 1000 for your conversion.
[1]
Answer: MB
6
Explain why a 10-megapixel image (3872 x 2592) looks 'better' (clearer) than a 2-megapixel image (1600 x 1200) when printed on a large poster.
Refer to pixels in your answer.