First let me say I am very much a newbie when it comes to scripting Photoshop, but I have a very general question with regards to preview types in Photoshop. I understand it’s possible to use options when saving to assign a specific preview type using constants (eight bit Mac OS, eight bit TIFF, etc)… but is it possible to read in that value in a script, like can be done with properties?
As far as I can see, it doesn’t appear that Photoshop allows you access to this information. I could see no difference in the “File Info” panels for the same image saved with and without a thumbnail.
My best guess for a solution would be to install ExifTool https://www.sno.phy.queensu.ca/~phil/exiftool/l and use “do shell script” to have ExifTool get you the thumbnail information on an image.