How to Remove a whitebackground but keep the shadows?
some times its easier to get rid of the background and then re-add the shadows back in
can you upload an example and then I can give you more direct directions
Duplicate the picture layer in photoshop. Select and mask the top one without the shadow and put the bottom untouched layer on multiply blending mode… Then add a background underneath and your picture should be perfect
If you want to bring the selected image into illustrator/indesign on a background there, then do the same thing, but save 2 files. 1-Selected image with no shadow 2-Full image
When you bring both into the other program put the full image directly underneath the selected one and put it on multiply