FTM has no ability to look in to an image file, to tell what is in the image. (To my knowledge no program has this ability)
Since to my knowledge there is no way to attach a flag to a media file ie place in a category, you would have to develop a work around.
On such work around that comes to my mind is to append each media file with a code. For an example if the file is a picture.change: JohhDoe.jpg to IM_JohhDoe.jpg if it is a census change: Census1850.jpgto CS_Census1850.jpg