Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.2 9/18/84; site petrus.UUCP Path: utzoo!watmath!clyde!burl!ulysses!allegra!bellcore!petrus!karn From: karn@petrus.UUCP Newsgroups: net.video,net.analog Subject: Re: Q-channel bandwidth Message-ID: <304@petrus.UUCP> Date: Tue, 5-Mar-85 14:35:26 EST Article-I.D.: petrus.304 Posted: Tue Mar 5 14:35:26 1985 Date-Received: Wed, 6-Mar-85 04:58:45 EST References: <146@unccvax.UUCP> Organization: Bell Communications Research, Inc Lines: 14 Xref: watmath net.video:1036 net.analog:184 My understanding of the reason for the different I and Q channel bandwidths is that it was based on human visual perception. The human eye is much more sensitive to changes in intensity and hue for some colors (e.g., flesh tones) than it is in others. The I and Q axes were arranged so that the I channel carries the information requiring wide bandwidth (reddish-yellow flesh tones and their complements) while the Q channel carries blue-green signals and their complements. The eye is much less sensitive to bandwidth restrictions in the Q channel. Given its age, NTSC is still a remarkable tradeoff between human factors and engineering constraints, which is even more amazing when you consider that it was produced by committee. Phil