We all love looking at the 4K RED frame grab files that have been posted so far as TIFFs and DPXs.
But, 16bit PNGs may be a better option. Example: The Skytower DPX file posted is over 32MBs is size. A PNG (16bit color depth) of Skytower is less than 13MBs. That's nearly a 2/3 download time and hard drive space savings. The PNG is just as good, in fact, it is exactly the same.
Just make sure you use the 16bit version of a PNG and not the 8bit flavor.