Ah, that explains why I was able to navigate the menu but not the dialog. Thank you, deanishe.
What I'm trying to do is manipulate the UI to change the area from the whole image to a specific area; it's the pulldown at the bottom of the dialog. Each image I need to do is made up of over a hundred smaller images, and I have multiple of the large images. I then need to covert those smaller images into different file formats. But you got the gist, and I was afraid it might mean using code to do it. I'm going to check out Keyboard Maestro. It originally appeared in my search for "tools to automate Mac tasks" along with Alfred. I ended up with Alfred cause it seemed more robust, and while I still think it is true, I also think it's a case of using a sledgehammer to hang a picture frame: more of a thing doesn't necessarily make it suitable for the job. I may still be able to use Alfred.... perhaps in converting the files.
Thanks again.