Set the opacity of an image/colour

[anthony]

Fisrt just changing the specific color WILL NOT WORK!

This will not take into account that the image contains anti-aliased pixels
that is various shades of grey along the edges of the text to make it look smoother without staircase 'jaggies'.

A black and white image like this should be thought of as a mask for
other images, weither they are transparent, a solid color, a tile, or a photo.

To use it in this way see Channels and Masks, in IM examples
Using Masks with Images http://www.cit.gu.edu.au/~anthony/graph ... els/#masks

This show the three basic ways masks are used to pick foreground and background colros from different sources (images).