What makes 4K significant is that it is beginning to be implemented into the home theater environment via some 3D-TVs and 3D video projectors.
The 3D TVs and Video Projectors currently in use that employ the Passive Polarized Glasses method of viewing, resolution of the resultant 3D image is cut to 540p (960x540 pixels) for each eye, which is 1/2 1080p resolution. In comparison, the same TV displays a 2D image in 1080p resolution.
However, by employing a 4K resolution panel or screen, 3D images viewed via Passive Polarized Glasses can be displayed with 1080p (1920x1080) resolution for each eye. The additional bonus is that when viewing 2D images on the same TV, the viewer will see a full 4K resolution image.
However, it is important to note that there is no video source material available for the consumer market that is actually 4K resolution, whether from a Disc or TV transmission. The TV, video projector, or outboard video processor, has to upscale the incoming 3D or 2D signal to the desired 4K resolution.
On other hand, 4K resolution is now being employed in commercial digital cinema projection, where films are shot or mastered in 4K, or upscaled from 2K (1998x1080 for 1.85:1 aspect ratio or 2048 x 858 for 2.35:1 aspect ratio).
