[Coco] again: CoCo RGB to VGA conversion

[KnudsenMJ at aol.com]

In a message dated 8/19/04 6:45:40 PM Eastern Daylight Time, RJRTTY at aol.com 
writes:

>       Also, the presence of broadband noise can be a  good thing.  It
>  makes our NTSC television pictures look better than they should.
>  When you see a diagonal line on a monitor with high definition, you
>  will see a "staircase", but add a little broadband noise and you
>  get a softer and smoother line. 

Actually that smooth line is not a product of broadband noise dithering 
(though that would indeed help somewhat), but TV shows such lines as smooth because 
the signal is analog, and has all the shades of light and dark in between.

If you draw a line in monochrome black and white, you will get jaggy 
stairsteps.  If you "anti-alias" the image by using intermediate shades of gray, you 
will get a smoother looking line.  TV cameras just do that automatically when 
they scan the real-live image.

But given that the Coco outputs only a few brightness levels, deliberately 
mixing in some noise to dither the stationary image might be a good idea.  This 
assumes the LCD monitor (or any monitor) is analog or otherwise able to 
reproduce many intermediate levels of brightness.  --Mike K.