# Graphic file sizes calculations

We covered this in class last week. Forrester have a good concise article on this subject

1. 600 x 300 pixels, 24 bit colour depth

2. 600 x 400, 16 bit colour depth

3. 600 x 600, 24 bit colour depth

4. An image is 6 inches by 8 inches, and has a resolution of 1200 dpi. It has a bit depth of 20.
(a) How many colours can the image store?
(b) What will be the file size of the image?

5. A photograph measures 10 inches by 7 inches, and has a resolution of 400 dpi. The number of colours each pixel can store is 65536.
(a) What is the bit depth of the image?
(b) What will be the file size of the image?

## One thought on “Graphic file sizes calculations”

1. Mr Stratton says:

Always round up your answers for storage questions. If you round down you risk not being able to fit a file on the free space on a storage medium

1. 527.35 KB (600x300x24 bits)
2. 1.84 MB (600x400x16 bits)
3. 1.03 MB (600x600x24 bits)
4a 1048576 colours (2^20)
4b 164.8 MB (6x1200x8x1200x20 bits)
5a 16 bit (2^16 = 65536)
5b 21.37 MB (10x400x7x400x16 bits)