Submitting an image file for indexing generates the tokens "IMAGE" and "1"

Question

This is a problem because the user is able to submit any file through a web interface, and we want to determine when there is zero output from the indexing process so we can warn the user that the file they submitted has no indexable content.
I'd rather keep the detection algorithm simple: currently it checks to see whether any tokens were indexed for the record the user just edited, and IF there were NO tokens, the user is warned that the file they submitted contains no indexable words. But if ctxhx.exe generates the string "Image 1" when someone gives it (for example) a jpeg file, that's not going to work.
So my questions are these: How do I prevent ctxhx from generating any tokens when someone gives it an image file? And if that's not possible, how can I include logic in a batch file to detect an image file and prevent ctxhx from handling it? (Since the files are renamed without extensions when indexed, I can't determine file type from extensions). I know there's a command-line program called TestForPDF.exe, which I found at http://www.oracle.com/technology/products/text/htdocs/altfilters.htm; is there a similar program (perhaps TestForImage.exe), or instructions for creating such a program?

Answer 1

I finally resorted to using the "format column" feature of the context index. The code in my front-end looks at the extension of the file submitted by the user, and sets the value of the format column to "IGNORE" before it tries to resync the index. It seems a bit kludgy, but it works.