4K

• 4K is the new higher resolution now being required by some film distributors and broadcasters, which supersedes HD and 2K.
• 4K is also known as Ultra High Definition (UHD)
• In pixels this is 3840x2160

HDR

(High Dynamic Range)

Is a new standard designed to give viewers more detail in to the highlights of the picture on TVs that support UHD with HDR (known in shops as Ultra HD Premium). The current HD colour space standard is REC709 (also known as SDR - Standard Dynamic Range), which has a limited range of colours compared with the new REC2020 colourspace adopted for HDR. This means that there will need to be two different colour grading passes between the REC2020 HDR versions and the REC709 HD versions and the deliverables are separate.

More information can be found in this article: http://www.pocket-lint.com/news/136329-what-is-ultra-hd-premium-and-why-does-it-matter-the-4k-hdr-badge-explained

SDR vs. ST2084 HDR Image courtesy of Light Illusion http://www.lightillusion.com/uhdtv.html