By Michael Karagosian
While most people are aware that the DCI Specification calls for a compatible distribution of images having either 2K or 4K resolution, there are several related issues that are worth explaining. One of these is the natural limit in resolution of 3D images.
A 2K image, as delivered to the cinema, has either a width of 2048 pixels, or a height of 1080 pixels. For 4K, these numbers double, allowing either an image width of 4096 pixels, or an image height of 2160 pixels. Digital cinema picture data is compressed using the JPEG2000 algorithm, the nature of which allows a 4K image to contain a 2K image. This feature allows a single 4K distribution to play in either a 4K or a 2K server and projector.
