Rescale based on longest side?

[danvolkens]

Do any of the dim rescale options resize the longest side of an image, whether it's width or height? E.g. dim="250<>"? From what I can tell, I can specify a fixed width or height, but not specify the longest side. This is a necessity since uploaded images can be in either portrait or landscape format, and need to maintain a max width or max height of 250px for portrait/landscape respectively. Thanks!