You are suggesting the photos you see produced by GT5/GT6 photo mode are screencaps of the photomode running in realtime. This is incorrect. When you line up a shot in realtime, the quality is higher than gameplay, and probably a tad higher than replay (going by the way the framerate tanks), but it's still horribly aliased, and the shadows are very low quality. Detailed tessellation takes seconds to kick in, and when you take the shot, the PS3 then renders it veeery slowly at full quality. It takes several seconds to produce the frame, so certainly can't be described as realtime.