1.2 Multimedia – Graphics & Sound
AS Level · 1 question found
What this topic covers
Section titled “What this topic covers”- Bitmap images: pixel, file header, image/screen resolution, colour/bit depth
- Calculate bitmap file size; effects of changing resolution or colour depth on quality and size
- Vector graphics: drawing object, property, drawing list
- Justify bitmap vs vector for a given task
- Sound: sampling, sampling rate, sampling resolution, analogue vs digital
- Impact of changing sampling rate/resolution on file size and accuracy
Past paper questions
Section titled “Past paper questions” Q2
2
A photograph is stored as a bitmap image.
(a) The photograph has a resolution of 4000 pixels wide by 3000 pixels high. The bit depth is
4 bytes.
Calculate an estimate for the file size of the photograph in megabytes.
Show your working.
Working .....................................................................................................................................
Answer ...................................... megabytes
[2]
(b) The photograph is compressed before being uploaded to a web server.
(i) Give three benefits of this photograph being compressed using lossy compression
instead of lossless compression.
1 ........................................................................................................................................
2 ........................................................................................................................................
3 ........................................................................................................................................
[3]
(ii) Explain how run-length encoding (RLE) will compress the photograph.
..................................................................................................................................... [2]
(c) Identify two elements of a bitmap image that can be changed to reduce its file size.
1 ................................................................................................................................................
2 ................................................................................................................................................
[2]
,
,
Show mark scheme
2(a) [2 marks]
1 mark
for working:
4000 * 3000 * 4
1 mark
for correct answer:
48MB
for working:
4000 * 3000 * 4
1 mark
for correct answer:
48MB
2(b)(i) [2 marks]
1 mark
each to
max 3
:
The file takes less storage space on the web server than if lossless
compression was used
The file is faster to upload/download to/from the server than if lossless
compression was used
The file uses less bandwidth to transmit than if lossless compression was
used
The file consumes less data allowance than if lossless compression was
used
each to
max 3
:
The file takes less storage space on the web server than if lossless
compression was used
The file is faster to upload/download to/from the server than if lossless
compression was used
The file uses less bandwidth to transmit than if lossless compression was
used
The file consumes less data allowance than if lossless compression was
used
2(b)(ii) [2 marks]
1 mark
each:
Identifies
consecutive
repeating
pixels
of the same colour
Stores the colour /pattern and the number of times it repeats
each:
Identifies
consecutive
repeating
pixels
of the same colour
Stores the colour /pattern and the number of times it repeats
2(c)
1 mark
each to
max 2
:
Colour/bit depth
Image resolution
each to
max 2
:
Colour/bit depth
Image resolution