Re-combining separated channels in Image::Magick (Perl)

Hi folks.

I'm working on something that needs to do separate processing on the red, green, blue and alpha channels of a TrueColorMatte image. I can use the Perl API's Separate() method to separate out the four channels, but I can't find a way of combining them again, including the alpha/opacity/matte channel. I believe the -combine option of the command-line interface can do this, although I'm not sure that it supports the alpha channel.

Cheers, Jon.