4K refers to one of two high definition resolutions: 3840 x 2160 pixels or 4096 x 2160 pixels. Extension 2: Create the Backup of 4K Blu-rayīefore we go, somebody may still feel not clear about what 4K actually means and what benefits it can bring to us.Extension 1: Create Your Own 4K 3D Movie.Part 4: How to Watch 4K Video or 4K Blu-ray on PC.Part 3: 5 Best 4K Video Player Software for Mac and PC.