DKA, on 07 September 2012 - 04:41, said:
So far this isn't possible. The only reason it went transparent for me was an error in the image format. Once the image format is corrected and you add transparency to it, the color you chose with the image will take over resulting in a transparent image with solid background behind it.
No, I get that it was done in error, I'm saying as a future option added by MS it could work. I'm sure one of the things at the top of the list when it comes to the start screen is being able to add your own background images to it. As we've seen though, doing so can often make it hard to see the live tiles clearly since they also don't have any type of depth and or thick border around them. So in the end if MS listens and does add this option in some future update to the OS like it sounds we'll be getting, then they'll have to tweak something in the UI to make sure the tiles are still distinguishable in the end.