Catalogs and Variants

I am trying to understand how variants edited with external programs such as photoshop are stored in the catalog.  I chose the add to catalog option when doing an import to keep the size of my catalog small.   So if I edit an image with an external progrm, it asks me the file type usually I use TIFF.  Make my edits and the file shows back in my catalog.  It appears that the whole TIFF file is stored in the catalog instead of just adding it to the catalog.  Is there a way to confirm this or change the default option so I don't have a huge catalog.

Thanks

Robert