New Post: Replace color with another

Here is an example of what I would like to do:

http://www.imagemagick.org/Usage/color_basics/#replace


For example to replace a 'blue' color with say 'white' you would use a command like this...

convert balloon.gif -fill white -opaque blue balloon_white.gif



I have found image.Fill() but am not able to find a way to specify what color to replace.

thanks for any help.