This is what I understand from your narrative:
- You have 24 databases. Each database contains .jpg images. And each database has Spotlight Indexing enabled. (I.e., in File > Database Properties … you have enabled “Create Spotlight Index” for each of the 24 databases – or at least for the databases containing images).
- You want a simple method to locate those images on the fly.
Open Finder. Create a search: command-F. Set the search parameters to this:
To get the latter part of this (“Any of the following is true”), after you enter the first line (“Kind is Other DEVONthink Pro Office Document”) hold Option and you will see the “+” turn to an ellipses ("…"). If you click the ellipses while Option is pressed you’ll get the next line (“Any of the following is true”) then you enter the last two predicates (“Name ends with .jpg” and “Name ends with .jpeg”).
Save the search (press “Save”).
Use whatever name you want. Save it to “Saved Searches” (the safest location for these things). Check “Add to Sidebar”.
Saved Searches are not static – they are like Smart Groups in DEVONthink – the results are updated to meet current conditions every time you click the saved search in the Finder Sidebar. The above setup is a one-time task, and from now forward you’ll only need to return to your saved search when you want to browse your images.
Whenever you want to find a jpeg in your databases, click that saved search in the Finder Sidebar. You’ll have a few options to locate your images with this saved search.
a) If you recognize the image name, double click it and that document will open in the database where it is stored.
b) If you want to browse images, select some or all of the images in the saved search (command-a) and press the space bar to open a preview window with a preview of the image(s)º
Use the navigation arrows to move back and forth through the selected set of images. Click “DEVONthink Pro Office” in the preview panel to open that image in the DEVONthink database where it is stored.
c) If you want a full-screen preview then make a selection (or all) as in (b), hold the Option key, click the Finder File menu and choose "File > Slideshow …. Or, make the selection and press Command-Option-Y to open Finder’s Slideshow display. Use Slideshow’s controls to navigate back and forth. In Slideshow double click the image you like and it will open in the DEVONthink database where it is stored.
Note that with the way DEVONthink interacts with Spotlight (which is a topic covered in a separate thread here a few days ago) that Finder’s Preview and Icon modes – and Slideshow’s thumbnail mode – do not work to show the contents of a file – only Quick Look or Slideshow work for this, which are the methods I described in (b) and ©.