Attached Link: http://www.boxofficeprophets.com/column/index.cfm?columnID=9121

"There are some 'shorthand' values that are used in describing the resolution of a digital projector. When we talk of the HDTV standard in the United States, we talk in terms of 'lines' (horizontal lines per image, or height), like 1080i (1,080 lines per image) and 720p (720 lines per image). Cinema projection is referred to by the width of the image, and uses two key terms: 2K and 4K. The 'K' represents the number 1,000 (like in the Y2K bug, where '2K' meant the year 2000), and the number represents how many pixels across (wide) the image will be. So 2K means 2,000 pixels wide, and 4K means 4,000 pixels wide. Specifically, a '2K' projector will have a maximum resolution of 2048 pixels wide by 1080 pixels high, while a '4K' projector will be 4096 x 2160. (It is not a coincidence that the 1080i HDTV standard has the same number of horizontal lines as the 2K cinema standard.)"