(PHP 3 >= 3.0.2, PHP 4, PHP 5)
imagecolorresolve -- 
    Get the index of the specified color or its closest possible
    alternative
   
Description
int 
imagecolorresolve ( resource image, int red, int green, int blue )
    This function is guaranteed to return a color index for a
    requested color, either the exact color or the closest possible
    alternative.
   
    If you created the image from a file, only colors used in the image are
    resolved. Colors present only in the pallete are not resolved.
   
    See also imagecolorclosest().