[BC] CBS Color...lived on - NTSC useable resolution

[Larry Albert]

NTSC produces a USEABLE resolution that is nearly 440 x 330.

   The USEABLE vertical resolution is 330 horizontal lines (165 black and 
165 white )and is limited by the number of scanned lines and the Kell Factor.

   The Useable horizontal resolution is 440 vertical lines; 220 line pairs.

   The general use of 330 for horizontal resolution is because a horizontal 
width equal to the vertical height is used for the determination.

   *******  Math follows *****

   Video Bandwidth = 4.2 MHz

   Period of one cycle of 4.2 MHz = .2381  microseconds

   Active video period of a horizontal line = 52.66  microseconds

   52.66 / .2381  =  221.17

   NTSC has a possible TRANSMITTED horizontal resolution of 221 line pairs 
(442 lines).

*****  Math Ends ******


NTSC  approximately 440 x 330

  VHS  approximately 320 x 240




At 08:42 PM 6/3/06 -0700, you wrote:
>James, at the risk of furthering the list's reputation for nit-picking, I 
>would like to add a couple of comments to yours:
>
>In a message dated Wed, 31 May 2006 19:39:14 -0400, James Snyder 
><broadcastlist at dtvexpress.net> writes:
><<
>>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 decimation
>>of luma frequencies to fit the 3.58 subcarrier, which produces about
>>80 lines of chroma resolution.  For the sake of compatibility we gave
>>up a third of the potential luma resolution.
> >>
>
>First, I believe you are confusing horizontal and vertical resolution.
>
>The vertical resolution of NTSC is 525 lines, but some of those lines are 
>consumed by sync, leaving about 500 lines of actual, active vertical 
>picture information. NTSC's vertical resolution is not modified by 
>bandwidth limitations, and is identical for the B/W and color standards, 
>i.e., about 500 lines vertical resolution.
>
>According to Donald Fink's "The Forces at Work Behind the NTSC Standards" 
>at <www.ntsc-tv.com>, the CBS system was an incompatible 405 (not 441) 
>vertical line system. I'm not sure how many of those 405 lines were used 
>for sync, but I think we can safely assume that, in addition to being 
>incompatible with existing B/W sets, the CBS system had about 20% *less* 
>overall vertical resolution than NTSC.
>
>The "330" you quote is for *horizontal* luminance resolution, which is 
>where the first NTSC compromise occurred. Horizontal resolution IS 
>bandwidth-dependent. While they aren't really 'lines' but rather the 
>maximum number of black-to-white (or vice-versa) transitions per 
>horizontal line, 330 'lines' is indeed the typical maximum in the 
>luminance channel for an NTSC broadcast transmission.
>
>And therein lies another possible source of confusion: Because 
>fully-compliant NTSC resolution can be better (and is, in the studio 
>before transmission), the real limitation is indeed the transmission 
>medium (over the air and cable), a bandwidth restriction imposed by the 6 
>MHz analog broadcast channel. Before it hits the transmitter, NTSC video 
>can actually look pretty damn good.
>
>The horizontal chrominance bandwidth for NTSC is where we really lose out 
>(typically **40** lines, 80 at best), and where the CBS system was far 
>superior. NTSC color transmission, (kind of like MP3 for audio) took 
>advantage of human eye's lesser sensitivity to chrominance than luminance. 
>Since the vertical resolution for color is not compromised in any way, it 
>was acceptable to most consumers. And in the 1950s, what could they 
>compare it to?
>
>Even in SP mode, standard VHS VCRs rarely had a horizontal luminance 
>resolution of better than 230 lines; *much* less for chrominance. At the 
>other end of the scale, S-VHS and Laserdisks (both analog) can do better 
>than 400 lines horizontal luminance and DVDs (pure digital) can exhibit 
>resolution in excess of 500 lines, all the while still following the NTSC 
>standard. (S-video's claimed capability for horizontal chrominance 
>resolution is 120 lines.)
>
>Aside from the occasional green face and horizontal color smearing, the 
>thing that really annoys me about NTSC color is 'dot crawl,' which 
>Faroujda and others sought to fix, with mixed results.
>
>
>
>Kind Regards,
>David
>
>
>