How do I import a photoshop file into AE (5.5) and preserve the background transparency?
I aways get a black or white background. I'm trying to composite a simple looped animation
against a video background.
Unless you specifically create an alpha channel in PS, you need to ensure that whatever image you create is over the "checkerboard" background in PS. Then when you import into AE, interpret the alpha channel as straight. If you work in PS over the checkerboard (transparent) background and save the file as a Photoshop file, it should import correctly into AE.