How to tell the quality of an image?

I have 2 JPEG image files open in PS; one was saved with a quality setting of 10, and the other saved with a quality setting of 12.  When I switch between the 2, and do a Save As on each one, the JPEG Options dialog accurately reflects the quality setting of each one.

I would like to be able to query PS, from my application using an AppleScript, for this information.  Is that possible, and if so, how?

The reason I want to do this is, my application opens a number of files in PS for editing; in this particular case, my client would like to always save the images as a JPEG quality 12, so as to reduce the risk or artifacting (which is more evident at, say, even the 10 quality setting).  However, if the image has *already* been saved with a quality setting of 12, I'd like to not add yet another extraneous file save to the mix.  Thus, if I can ask PS for the quality setting of the image, then I can decide whether to tell it to save it at the higher quality setting or not.