[NTLUG:Discuss] OT - re: tv resolution

[Fred]

On Sun, 17 Apr 2005 Steve Baker <sjbaker1 at airmail.net> wrote:

>No - the vertical resolution of a single NTSC field is 262
>and a half scanlines.  

Pardon me. The standard for video resolution is TVL, or
horizontal lines. That is how many vertical stripes can be
resolved by a tv display, not how many scan lines there are
in a picture.

>The horizontal resolution is impossible to define because
>NTSC is an analog system. 

Not true. You measure it with a test card.

>However, your PC (if properly set up) should be able to
>produce graphics at least as good as broadcast TV. But using
>a PC tuner to grab images - then display them on the TV may
>not produce such good images because of inevitable losses in
>the NTSC->RGB->NTSC conversion process.

"Losses"? There are the inevitable artifacts generated by
the scan conversion process and there is an inevitable loss
of resolution in an analog RF tranmission loop (tuner) as
compared to direct video input. What you get on your computer
display is as much a function of the underlying display
software than anything.

I regularly watch dvds on my computer and they look better 
there than on my tv, so I would say that the computer
graphics
are better than broadcast TV, IF the software is right. 

>Using an NTSC TV as a monitor is usually a disasterous idea.

So true, mainly because the bandwidth of the video circuitry
of the tv set is not sufficient to adequately display PC 
graphics. That is the main reason why Apple chose a 40 line
display and an rf modulator-to-tv set for a monitor and Tandy
chose a 64 line display and a dedicated monitor for their 
system. Cost vs performance and all that. With a tv, Apple
could deliver color graphics. To keep the cost down, the
Tandy
systems were monochrome.

If you want high res video, get a scan converter and use a
vga
monitor. If you want to use a tv, put up with crappy
resolution. 

Fred Stevens
Stevens Systems
Video Surveillance

ps - this thread is way off of linux stuff, so any replies
should be off-list.

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