I use the XMPScript API with a JScript for Photoshop to get files image properties (width and height) before to import them. It work well but SGI and OpenEXR files don't have width/heigth information in the Metadata. I would like to know if it's possible to figure out this problem.
For example, how ACDSee can get this information for SGI files ?
Bridge has an alternate interface for accessing metadata from image files. You may be able to get the values you need that way. The other alternative is to call exiftool via app.system(), have it dump its results to a text file and see if what you need is in there.
Plenty of Applescript freebies - Can you convert to AS for this task? If so, I believe can send one to you.