function CompareRGB(master, current: TColor32; tolerance: Integer): Boolean;

A callback function that can be passed as a parameter to various functions. This function compares two colors and returns true when the hue of 'current' is within 'tolerance' of the hue of 'master'. (While the alpha channel of 'master' is ignored, if the alpha channel of 'current' is less than $80, then the function will return false.)