bolle@ecrc.de (Andre' Bolle) (12/05/90)
I think there are hue differences between the European and US TV colours. 1. Am I right? 2. How were the different colour encoding schemes chosen? andre'
myers@hpfcdj.HP.COM (Bob Myers) (12/11/90)
>I think there are hue differences between the European and US TV colours. Hell, there are differences between US TV colors and US TV colors! (Remember, NTSC = "Never Twice the Same Color!" :-)) >1. Am I right? If the world were perfect and everything worked according to specs and theory, the differences between the two systems would be very minor, assuming that each started with the same info in RGB space. (There are, I believe, some differences between NTSC and either PAL or SECAM as far as color bandwidths, but these don't exactly relate to the encoding scheme itself, and what their independent contributions would be I knoweth not.) >2. How were the different colour encoding schemes chosen? I'd like to hear more about the history of PAL and SECAM myself. The US NTSC standard basically grew out of the requirement - imposed by the FCC - that any color encoding standard would have to be completely compatible with the then-current monochrome standard (basically RS-170) in order to be accepted for use in this country. The amazing thing is that the NTSC actually came up with such a thing, in 1950s technology; it's definitely a bizarre system at first glance. Bob Myers KC0EW HP Graphics Tech. Div.| Opinions expressed here are not Ft. Collins, Colorado | those of my employer or any other myers@fc.hp.com | sentient life-form on this planet.
tgg@otter.hpl.hp.com (Tom Gardner) (12/12/90)
From possibly incorrect memory: - the transmission path between the transmitting and receiving aerials can introduce phase distortions - in the NTSC system these distortions appear as changes in hue - in the PAL (Phase Alternation Line) system the distortion between two successive lines is cancelled by adding the complement of one line to the next. This converts the changes in hue into changes in saturation. - this is an improvement because the eye is less sensitive to changes in intensity than to changes in hue The PAL system is fully compatible with the preceding monochrome systems. The major extra component required for a PAL set is a 64us delay line.