Bitmap file size calculation
I can explain how resolution and colour depth affect the file size of an image.
Bitmap file size calculation
I can explain how resolution and colour depth affect the file size of an image.
Lesson details
Key learning points
- The file size of a bitmap is determined from its colour depth and resolution.
- Increasing the colour depth of an image will increase its file size.
- Increasing the resoultion of an image will increase its file size.
- Selection of image resolution and colour depth depend on the use of the image and limitations imposed by the file size.
Keywords
Trade-off - accepting a limitation to achieve a beneficial outcome
Common misconception
Using a low resoultion or colour depth for an image makes it unusable.
A low resolution or colour depth does not necessarily make an image unusable. It depends on the purpose. Lower settings can be suitable for web use, icons or thumbnails, while higher quality is needed for printing or detailed graphics.
Equipment
Licence
Lesson video
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Prior knowledge starter quiz
6 Questions
Q1.What is the basic unit of data in a computer system?
Q2.What does a character set do?
Q3.Which character encoding system uses up to 32 bits per character?
Q4.Match the terms to their definitions:
smallest element of an image
number of bits used per pixel
total number of pixels in an image
a group of 8 bits
Q5.How many states are possible with a sequence of 4 bits?
Q6.What does colour depth quantify?
Assessment exit quiz
6 Questions
Q1.Place the following file sizes in order from smallest to largest:
Q2.What determines the file size of a bitmap image?
Q3.Match the terms to their definitions:
accepting a limitation to achieve a beneficial outcome
total number of pixels in an image
number of bits used per pixel
suitable for web use or thumbnails
suitable for printing or detailed graphics