[BC] CBS Color...lived on

[Richard Fry]

James Snyder:
>The CBS system produced 441 lines with full resolution in both luma
>and chroma.  The NTSC compatible color system produces about
>330 lines out of the 525 line scanning standard because of the deci-
>mation of luma frequencies to fit the 3.58 subcarrier, which produces
>about 80 lines of chroma resolution.

To elaborate on this -- NTSC chroma vertical resolution is not ~80 lines, 
but the same as luma vertical resolution.  Every horizontal line can assume 
any color in a scene that is available in the NTSC gamut (which is larger 
than for printed images, BTW).

NTSC horizontal color resolution varies according to the color in the scene 
as it is scanned.  If the instantaneous chrominance value in the scene is 
carried mainly by "I" video, horizontal color resolution is about 120 lines 
(I video has about 1.5 MHz bandwidth).  If scene chrominance is mainly 
carried by "Q" video, horizontal color resolution is about 40 lines (Q 
video has about 0.5 MHz bandwidth).  Of course, the effective horizontal 
color resolution can vary between these two limits depending on the color 
in the scene at every point in the raster -- which sets the ratio of I&Q 
video in the transmitted chrominance waveform.

I&Q video bandwidths, and their phase offsets from each other and to the 
color burst signal were chosen to best accomodate mainly high-luma colors 
where the eye has greatest color resolution, such as for some flesh tones. 
This eliminated the need for equiband "hi-res" RGB signals -- which cannot 
be transmitted simultaneously in an r-f channel yielding ~4.2 MHz of 
demodulated video bandwidth.

>>2) Severe flicker on highly saturated primary colors in the scene

>This was a function of the display device.  If the display device was
>designed & implemented correctly, there was no flicker in highly
>color saturated portions of the picture.

My reference was to _primary_ colors (all R, G or B).   Any part of a scene 
having only one of those colors would be reproduced at the receiver with an 
application rate only 1/3 that of a monochrome image.  In a 525/60Hz system 
that produces a lot of flicker in those parts of the scene, unless the 
persistence of the CRT phosphors is so long that "tails" tend appear 
following moving images.

RF (RCA Broadcast Field Engr, 1965-1980, and installer/troubleshooter of 
many RCA color film and studio cameras)