Reducing the number of colours in an image with CS4?

[Feek]

I have an image and I need to reduce the colour count to below 100 colours, is there a simple way to do this in CS4?

[Joe 90]

Yeah really easy - just do a save for web and (with png at least) you can pick how many colours you save the file with. That way you can keep a higher quality image also.

[Feek]

Ta