It's hard to say because there is so little official information on how these titles are done. So, what I go by is the appearance of the saturation of color when played with a "TV" that has been calibrated for proper color.
Initially, I decided to select only "True 4K" productions as referenced by
http://realorfake4k.com/
I bought Chappie and Sicario, both are produced with 4K production and processing.
Chappie references "wide color Spectrum" but Sicario makes no mention of the color. Both are HDR.
When I play Chappie- I have to use BT2020 ( REC2020) Color Gamut to get the proper colors.
If I play Sicario with BT2020, the color is all washed out. So, I select BT709 (REC709) Gamut in the projector and the color returns to a natural saturation and the hues are normal.
I would assume that Sicario used a reduced color gamut somewhere along the way. The Hollywood industry standard for theaters is DCI P3 which offers higher number of colors than 709 but less than 2020. But in the production of the BluRay disk, the color gamut may have been cut back to 709, while the theatrical release was fixed to P3. Are you confused yet? Don't worry most people are and most are just guessing due to lack of official confirmation. To help picture what I am saying look at the color gamut chart of each standard that overlays the human eye range:
While all 4K UHD releases I have seen and the upscaling of 2K to 4K is the best I have ever seen, that will please most, the problem with these color gamut inconsistencies can cause color to appear worse than traditional Blu Ray 1080p movies. Unless you do a very careful calibration of the TV and then manually select the proper calibrated color gamut for each movie release youm may be paying for 4K UHD but not getting your money's worth due to the TV not being calibrated for the way the disk was produced!
OK that sucks! UHD 4K is just not ready for simple plug and play yet. Maybe next year, but for now we are early adopters. At least as of March, we have disks, player, and TV's that will do 4K. If you had a 4K TV before March 2016 you really didn't have all that UHD was able to offer yet and were "pre-early adopter."