Currently, you can limit the maximum dimensions for various image derivatives in the admin side of the site. However, you cannot specify if you want the dimensions to apply to length or width.
On the item/show pages of our site we have a horizontal space of 500px for our images. We have set the fullsize derivative to 500px. This works for resizing landscape pictures for that space, but not portrait pictures. The height of these pictures gets set to 500px, and the width is usually much smaller than the 500px space. After uploading pictures, we manually go through and replace the portrait pictures with ones that have a width of 500px.
Is there any way to limit derivative images size by a specific dimension?