File size of digital images
I can describe how image file sizes are calculated and how changes to image quality and colour accuracy adjusts this.
File size of digital images
I can describe how image file sizes are calculated and how changes to image quality and colour accuracy adjusts this.
These resources will be removed by end of Summer Term 2025.
Lesson details
Key learning points
- The colour of each element in a digital image is represented using binary digits.
- Changing image quality (resolution) affects file size: higher quality increases size, lower quality decreases it.
- Changing colour depth affects file size: higher colour accuracy increases size, lower accuracy decreases it.
Keywords
Resolution - the dimensions of an image in pixels, or the number of pixels per inch (PPI), which affects image quality
Colour depth - the number of bits used to represent a colour, which is also known as bit depth
File size - the amount of data a file contains
Common misconception
1 bit is always used to represent 1 pixel.
While bits are used to represent the colour of pixels, it's not always a one-to-one relationship. The number of bits used can vary depending on the colour depth of the image.
To help you plan your year 9 computing lesson on: File size of digital images, download all teaching resources for free and adapt to suit your pupils' needs...
To help you plan your year 9 computing lesson on: File size of digital images, download all teaching resources for free and adapt to suit your pupils' needs.
The starter quiz will activate and check your pupils' prior knowledge, with versions available both with and without answers in PDF format.
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The assessment exit quiz will test your pupils' understanding of the key learning points.
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Explore more key stage 3 computing lessons from the Data representation: images and sound unit, dive into the full secondary computing curriculum, or learn more about lesson planning.
Equipment
Licence
Lesson video
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Starter quiz
6 Questions
Exit quiz
6 Questions
dimensions of an image in pixels
number of bits used to represent colour
amount of data a file contains
enhances image clarity
decreases image clarity
enhances colour accuracy and richness
decreases colour accuracy and richness