Sony announced a new line of "Mastered in 4K" Blu-rays a few months ago. In short, they took a bunch of movies and created new 4K digital masters of them. They took those masters and carefully crunched them down to create new Blu-ray transfers of everything.
This resulted in discs that are not only (allegedly) better-looking than the previous Blu-rays, but are specifically optimized for up-converted viewing on new Ultra HD "4K" TVs. In addition to playing with the pixels so that they'll look better after upconversion, they've redone the color profile on these to take advantage of color gamut that only 4KTVs can display. These discs, like their Superbit DVD ancestors (more on them in a bit), lack any special features whatsoever.
The new "Mastered in 4K" Blu-ray of Ghostbusters ($15) is a vast improvement over its predecessor. That still doesn't make it a blind or instant buy.
From the 2013 "Mastered in 4K" Blu-ray, aka "how good the 2009 disc should have looked"
