Image optimisation is a necessity requirement for all web sites designed.
The simple reason being that if your images are not optimised, they will be larger and therefore your web site page will take longer to load.
This is something that you really don't want. Although many people now have broadband, the majority of users are still using dial-up connections with a 56k (or below) modem. It is therefore imperative, when designing a website that loading speed should be a big consideration.
Different web designers have different views on the maximum size a web page should be. In general however, pages that take more than 15 seconds to load are considered to be too large.
Example: Here are two images, without cheating, which one has been optimised? One of these images is 16K (approx 16,000 bytes) in size. The other is only 5K (approx 5,000 bytes)
If you look closely, you can see slight differences, however to the normal eye, it is the same image. The difference in file size however, is considerable.
IMAGE B has been optimised to 80% quality and is 5K.
But what does it all mean?
The table below shows an estimated example of how image optimisation can effect the time taken to display a page.
Non Optimised Size
5 images of simlar size to those above on a page
The pages text content and required html
Total Page Size
Approximate estimated time to load the page
These times are based on viewing a page on a 56K modem, (which doesn't actually connect at 56K. A more accurate speed would be approx 44K).
Based on the above table, a simple optimisation of images can make the web page show at less than half the time of a page which has not been optimised.