I've been trying to do this all day but can't get it to work.

What I want to do is modify my pictures with Photoshop and then put them back in the camera, I'd also like to this with video, is it impossible?

I have an Canon S80 and when I try to put a photo back in the camera it tells me that the photo was either not taken with a Canon camera or had been modified and cannot be put back in the camera. If I put them in my SD card they won't show up on the camera's LCD.

Anyway to do this.