4K (computer virus)
4k is a computer virus which infects COM files and EXE files. The virus was one of the first to employ stealth tactics. Infected systems will hang, after September 22 every year, which is also the date of birth Bilbo Baggins, a character from "The Lord of the Rings". The code was intended to display the message "Frodo Lives", but hangs in all known variants.
4K resolution
The 4K UHD standard doesn't specify how large the pixels are, so a 4K UHD projector (Optoma, BenQ, Dell, et al.) counts because these projectors have a 2718×1528 pixel structure. Those projectors process the true 4K of data and project it with overlapping pixels, which is what pixel shifting is. Unfortunately, each of those pixels is far larger: each one has 50% more area than true 4K. Pixel shifting projectors project a pixel, shift it up to the right, by a half diameter, and project it again, with modified data, but that second pixel overlaps the first.