Re: IIgs RGB to VGA experiment

["js@cimmeri.com" <js@cimmeri.com>]

> > Strangely, IIgs to the same monitors' composite ins really performed quite poorly, with or without color.

> Actually, that would be expected.  It would be quite unusual to detect the absence of the color burst and then expand the processing bandwidth of the video signal (as the
Applecolor //e monitor does).  The Y component input, however, is known
not to contain a chroma subcarrier, and so can be uniformly processed
with high bandwidth.

**** I understand now.  Does make sense.


> >    I do note that regardless of the size of the TV, the output still looked great.. even at 50".   Others have expressed the concern that a SMALL screen is required.   Apparently not true -- these TVs are *sturdying up* the lines and making them look good at large sizes.

> The lines *really are* that wide.  The effect is just one of "magnification".  If you don't mind the relatively low pixel count, then it will look fine--crisp but coarse.

**** I have to disagree with something here, though not sure what.
The lines are in fact much fatter than the actual screen resolution.  I
know this because -- I can create finer lines from other sources, and
also can see the pixels making up the lines.

For instance, the LCD monitor has a native res of 1280x1024.  I run a
PC with it at this res normally.    With the IIgs composite->Y
connector, the gs image fills the whole screen... even though the gs
res is much lower than the native.  So the screen appears to be
fattening up all the IIgs pixels by making pseudo fat pixels from
several native ones.  Same thing occurred on the Toshiba HDTV
widescreen.






> > What is the minimum resolution needed to correctly display all IIgs modes, up to SuperHires 640x200?

> The real answer will have more to do with the interpolation/scaling algorithm of the TV than the native resolution, since any digital display, even a CRT one, will pixellate the display.   Since it is *very* unlikely that the TV will attempt to lock to the Apple dot clock, results may be a little unstable unless the TV pixels provide more than 2:1 oversampling of the Apple video--which would be a *very* high end display.  ;-)

**** I'm confused (not hard to do).   As I imagine this, say I run the
IIgs at 320x200.   If I have an LCD that has a res of 1280x800, it
already has a pixel density 4 times greater than that IIgs res.   Is
that not equivalent to 4x oversampling?   The LCD wouldn't need to sync
to the II dot clock.. since one or more of those 4 pixels is going to
hit any one 320x200 pixel.   Until I run more extensive tests, I'm not
sure how this LCD would handle that particular case.. but it easily
displays the 640x200 res, for instance.. with no beat shadowing.

But still, I'm wondering about the IIgs RGB monitor, or even the
Commodore 1084.   If the IIgs 640x200 mode is displaying in the middle
of the screen with large borders, and IF you could, in theory, get each
of the 640x200 pixels visible individually, that would indeed mean that
the actual # of pixels for those monitors was somewhat greater than
640x200, correct?

Yet, I think what you are saying is that the approximate res of those
screens is 640x200... but that the IIgs is scrunching it's own version
of 640x200 into a smaller portion of those monitor's space.... using
less than 640x200.. such that one SCREEN PIXEL is actually a
combination of several IIgs pixels.   Do I have that right?   Should be
easy to find this out.

~ J