A-LevelComputer ScienceInformation representation9618/12 · Oct/Nov 2024 · Q77 Marks

A student takes a photograph of a science experiment.

(a)(i)The photograph is saved as a bitmapped image. Define the following bitmap terms. Colour depth File header[2]
(a)(ii)Explain why changing the image resolution will affect the image quality and file size. Image quality File size[2]
(a)(iii)Identify one lossless method of compressing an image.[1]
(b)The student draws a picture on paper that is scanned into the computer and saved as a vector graphic. Define the vector graphic terms property and drawing list. Property Drawing list[2]

Mark scheme

Marking points from the official mark scheme (Oct/Nov 2024). The mark or mark type is shown in brackets.

[2] 1 mark for each correct definition Colour depth: • the number of bits used to represent a colour // the number of colours that can be represented in an image File header: • stores data about the image file / metadata
[2] 1 mark for each correct explanation Image quality: • Decreasing resolution means details within the image are lost because there are fewer pixels // Increasing resolution means the image is more detailed because there are more pixels File size: • Decreasing the resolution will decrease the file size because there are fewer pixels therefore less data // Increasing the resolution will increase the file size because there are more pixels therefore more data
[1] 1 mark for correct method For example: • Run-Length Encoding
[2] 1 mark for each correct definition Property: • an attribute of a drawing object // data about a shape // defines one aspect of the appearance of a drawing object Drawing list: • all the drawing objects/shapes in an image // stores the commands/descriptions / mathematical equations required to draw each object

On Oracle Prep you can write or photograph your own answer and have it marked by AI against this mark scheme, with feedback on what you missed.