You will get a different result with ^ than leaving it off. Basically with ^ it resizes according to the smaller dimension. If left off it resizes to the larger dimensions. The latter is more suitable for extending and former to cropping. The > means that the image will only be resized if larger than the size provided. see
http://www.imagemagick.org/script/comma ... p#geometry
so if you are trying to resize and pad, then you can leave off the ^. if you are trying to resize and crop, then use the ^.
I don't see why PHP would have any trouble, if the geometry is either properly quoted or the ^,> etc are escaped. Though I don't use it that much. So I will defer to some other users, such as Bonzo, that use PHP more than I. See
http://www.rubblewebs.co.uk/index.php