How to make white space not visible or transparent around imagery

Discussion created by Grati31 on Mar 4, 2011
Latest reply on Mar 7, 2011 by timothy_hales-esristaff
I am working with two .sid files that overlap each other and at the overlap, is where I see the white space.  If I could just make it transparent (just the white space and not the rest of the image) then I could see my imagery without "white void".  I wanted to delete the white in Photoshop but .sids are not supported.  Any one know how to make the white not visible?