It's funny how they fixed bad opticals in some scenes but not in others. In that bird's eye shot of Luke and Vader dueling on that catwalk platform in ESB, when Luke blocks Vader and their sabers hit the railing, in the brightest flash-frame you can still see the bright light suddenly stopping at the boundary between the live footage and the matte painting. It was not recomped to make the light spill over into the painting, not in 1997, 2004, or 2011. Just interesting how they continue to make unnecessary changes while neglecting actual annoying flaws.