File Size Reduction (Cambridge (CIE) IGCSE ICT)
Revision Note
File Compression
What is file compression?
File compression is reducing the size of a file in order to take up less storage space and make file transmission faster
Images are often the largest element of a file and can be resized/resampled by:
Reducing the resolution
Reducing the colour depth
Resolution
Resolution is the total amount of pixels that make up an image
The resolution is calculated by multiplying the height and width of the image (in pixels)
In general, the higher the resolution the more detail in the image (higher quality)
Reducing resolution decreases the number of pixels and therefore reduces file size
Be aware that reducing resolution can cause a loss of image quality, especially when viewed at larger sizes
![10-1-images-image-editing-06](https://cdn.savemyexams.com/cdn-cgi/image/f=auto,width=3840/https://cdn.savemyexams.com/uploads/2023/06/10-1-images-image-editing-06.png)
Colour depth
Colour depth is the number of bits stored per pixel in an image
The colour depth is dependent on the number of colours needed in the image
In general, the higher the colour depth the more detail in the image (higher quality)
Reducing colour depth means using fewer bits and therefore fewer colours, which can reduce the file size
Like with resolution, reducing colour depth can lead to a loss of image quality
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