The HDMI 1.4 specification adds support for extremely high video resolutions that go far beyond today's 1080p systems. 4K is shorthand for 4,000 lines wide by 2,000 lines high, or roughly four times the resolution of a 1080p display. The term actually covers two formats, both supported in the HDMI 1.4 specification:
3840 pixels wide by 2160 pixels high
4096 pixels wide by 2160 pixels high
4K displays will put high-end home theater systems roughly on a par with the state-of-the-art Digital Cinema projectors used in many commercial movie theaters. Staying true to its commitment to future-readiness, the HDMI standard can now support these systems with the extremely high bandwidth connectivity they will require.
How to Ensure 4K functionality in your Home Theater System
Look for devices that support 4K functionality.
All High Speed HDMI cables will support 4K functionality when connected to 4K devices. You can use your existing High Speed HDMI cables or choose a different cable type. (more)