Graphic Optimisation

Although GIF, JPEG and PNG image formats are compressed, optimisation will significantly reduce the file size, and improve page download times.

In the optimisation process, you need to balance file size against display quality. The following all affect file size:

• bit depth (number of colours)
• interlacing or progression
• transparency
• dithering (mixing of available colours to give appearance of more colours)

Photoshop and Fireworks provide very easy to use optimisation controls.