and fix the callers to intepret the new format. Since this is a private procedure and it is only called in two places, and only one place actually uses the dimensions part of the size specification.
That sounds like a good suggestion. The only problem I foresee with that is that putting -strip in there will cause an error on earlier versions of ImageMagick.
It would also be useful to apply a change to the xowiki specific image resizing code.