How to filter out the pictures?

Handled something very similar recently with help from a colleague, a spreadsheet and a DOS box – compared a list of referenced graphics (thanks to FM) with a list of all graphics in the directory (thanks to the Copy as path) and created a discard.bat from the results :-}

A reliable and re-usable script would have been far more elegant, but as someone whose only programming experience is Pick DataBasic plus a bit a ColdFusion I'm not sure about the ROI for me :-}

What version of FM?

If it's 11 or 12, there may be an Archive hack you can use to essentially un-archive the unneeded imports.

If you want to write a script to process MIFs, grep for:

grep ImportObFile *.mif
grep TiSrcFile *.mif

The results can then be parsed to create a list of used imports, and perhaps move them. Delete what's left.

For a small number of imports, it's probably easier to move everything to a subdirectory, open the document, then move back each file as FM complains about it. Then delete the subdir.