# Graphics Calculations

Homework Due Wednesday 12th September

Work out the file sizes of the following graphic files, the answers should be given in an appropriated unit.

 Length Breadth Bit Depth 640 480 8 800 600 8 1024 768 8 1280 1024 8 640 480 16 800 600 16 1024 768 16 1280 1024 16 640 480 24 800 600 24 1024 768 24 1280 1024 24

# 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?

# Calculations in computer systems

I was sure I had this here already but I can’t find it.

Here are the main formula we used in the computer systems unit

• Largest number with n bits = 2n-1
• No of memory locations/different colours = 2n
• Coloumn heading in a binary number at n bit =2n-1
• Size of bitmap = no. of Horizontal pixels X no. of Vertical pixels X Colour Depth
• No. of pixels = DPI X size in inches
• Total storage capacity = no. of memory locations X location size.

You should also be able to convert from bits, Bytes, Kilobytes, Megabytes, Gigabytes & Terabytes.

• Bit= 1/0 (Binary digIT)
• 1 Byte = 8 Bits
• 1 Kilobytes= 1024 Bytes  (210)
• 1 Megabytes= 1024 KB  (220)
• 1 Gigabytes = 1024 MB  (230)
• 1 Terabytes = 1024 GB  (240)

For colour depth

• 8 bits = 256 colours (28)
• 16 bits = High Colour 65,536 colours (216)
• 24 bits = True Colour 16,777,216 colours (224)

# Homework for Thursday 1st Dec

Answer the following questions.

Convert the following to decimal

1. 11111100 (2’s comp)
2. 00110110
3. 11111111 (2’s comp)

How many pixels in the following files

1. 320×240 @ 8 bits/pixel
2. 1024×768 @ 16 bit colour depth
3. 1280×1024 @ 24bpp

What are the sizes of the following files in bytes

1. 320×240 @ 8 bits/pixel
2. 1024×768 @ 16 bit colour depth
3. 1280×1024 @ 24bpp

Calculate the storage requirements for the following images in Megabytes (to 2 decimal places)

1. 1440×1080 @ 24 bpp
2. 1920×1080 @ 24 bpp
3. 7689×4320 @ 24 bpp

# Photoshop Tutorials

I have added some new photoshop tutorials and resources to the Glow learn group.