PerlMagick is an object-oriented Perl interface to ImageMagick. Use this forum to discuss, make suggestions about, or report bugs concerning PerlMagick.
If the images contain transparency and are already 500x500 pixels, then just use -background black -alpha remove to remove the transparency from the coalesced images.
In API's the \( .. \) is just a new 'magick wand, or image sequence and -coalease is a shell api short cut for -layers coalesce