Multilevel grey scale or composite video to rgbi decoder

Abstract

A decoder apparatus (200) provides an R,G,B,I video drive signal in a TTL type of format from a received composite video input signal which comprises sync information and displayable information, such as conventional black and white video or a digitally encoded color video signal comprising a sixteen level code for providing sixteen possible color combinations of R,G,B, and I, without loss of bandwidth. The decoder (200) includes means for receiving the composite video input signal (202,10) and restoring it into separate DC restored sync (20a, 20b) and black and white or color video display information (30, 40, 50), both of which may be displayed on the same RGB monitor (107). White reference level signals are dynamically provided from the sampled video information and are used by a flash converter (100) in converting grey scale digitally encoded color video information into the TTL format R,G,B,I type of video signal (60, 70, 80a, 80b, 82a, 82b, 82c) which recovers the origianl R,G,B,I color signal. A fixed white reference level signal (84, 82 ) is used in place of the dynamically sampled white reference level signal when the detected composite video signal is black and white. In the instance of black and white, a pair of bits, through mapping, are used to determine the make-up of the TTL format based on the fixed reference signal, with the MSB representing the half point in the analog domain for the reference signal and the NSB representing the quarter point. Thus, a code of 1-1 represents full intensity white, 1-0 represents grey, 0-1 represents low intensity white, and 0-0 represents black.