I don't think I've ever read that. I thought the intention of scanning at 4K is so you get more of the film resolution in your master before you have to downconvert to 1080p. Supposedly starting w/ a 4k master produces fewer artifacts at 1080p.
The master resolution wouldn't affect how the 1080p image is then displayed on a 4k display. I could easily be wrong, so please correct me.
Well, this is specifically a Sony thing, and doesn't apply to any non-Sony releases where the movie was scanned at higher resolutions (for example, Criterion Collection).
Sony has a small line of about fifteen movies (maybe twenty or so by now) that are labeled as "Mastered in 4K" and "Optimized for 4K Ultra HD TVs."
I only vaguely remembered the details, so I looked this up. Specifically, these particular Sony releases are encoded using extended color XvYCC (whatever
that means), which other blu ray releases don't have. So it's supposed to take advantage of the color display capabilities of blu ray players and UHD TVs that have that spec, though the up-scaling to the higher resolution will be just like normal.
So it's like the blu ray equivalent of the "Superbit" DVDs (which was also a Sony thing). For example, there is the normal blu ray release of Spider-Man (2002), and then there is the "Mastered in 4K" version, which costs twice as much as the "normal" version but has no special features at all.
Kor[/QUOTE]
I've seen the Mastered in 4K Blu-Rays and it's really just marketing hype. It's the same as when you picked up a DVD (such as Star Trek The Animated Series) and it says "Mastered in 1080p High Definition. The DVD is not giving you a 1080p image, what it is giving is an SD 480i/p image that is of higher quality due to it being derived from a 1080 source rather than a 480, possible analog, source.
And Sony's claim about increasing the color is interesting, as a Blu-Ray stores it's color in the 4:2:0 manner, just like AVCHD and SD DVD's, but then the player (and on some players you can turn this off) upon playback converts it to a 4:2:2 or 4:4:4 (on a PS3 this is under the Video Settings: BD/DVD-Video Output Format (HDMI) setting where you can leave it at Automatic, or you can go to RGB [4:4:4] or Y Pb/Cb Pr/Cr [4:2:2]) color space.