BD or upscaled DVD

[Sharc]

Is there a means or a procedure to verify if a "Blu-ray" clip has been authored in real BD resolution, or if it is simply based on an upscaled DVD source? I had ocasionally some doubts.

[nurbs]

At avsforum.com they post comparisons between DVD upscaled to 1080p and blu-ray. For a quick comparison you can take a frame (preferably an I-frame with lots of visible detail), resize it down to the appropriate DVD resolution and resize it up to 1080p again and then compare it to the original. The more difference, the less likely it is that it's just an upscaled DVD. It's not 100% reliable, because it different movies and different frames don't have the same amount of visible detail. They could also add grain after the upscaling to make it look more detailed.