Re: Apple IIgs Color Dither Problem

[Immortal Nephi <Immortal_Nephi@hotmail.com>]

On Sep 16, 12:37 am, "Michael J. Mahon" <mjma...@aol.com> wrote:
> Immortal Nephi wrote:
> > Please explain why CRT / LCD screen for VGA monitor show colored
> > vertical strip which is called dithering, but real Apple IIgs' monitor
> > does not show dithering.
>
> > Do you have a way to combine dithering into solid true color on any
> > Apple IIgs emulator?  I know that 640x200 resolution has only four
> > colors each horizontal line.  You may need color dither translation
> > table.
>
> As Eric pointed out, the resolution of a modern monitor is much better
> than the Applecolor RGB, so the dithering--which is supposed to be
> averaged out to be useful--is resolved into fine lines of blue and
> white.

I apologize not to explain clear.  I did not say that CRT / LCD screen
for VGA monitor is connected to Apple IIgs' RGB port.  I simply talk
about Apple IIgs' real RGB monitor and VGA monitor.

> If you are not seeing 640 fine lines, but a considerably smaller
> number, then you are seeing a moire pattern formed by the "beat"
> between the 640-pixel dithered line and the LCD's real pixels and/or
> its resampling clock.

Michael pointed that Apple IIgs' real RGB monitor does not show
dithering because it does not have higher frequency so colored
vertical strip is harder to be seen inside the screen.  For example,
AppleColor monitor does not show black vertical strip on HGR / DHGR
screen because it is on 3.58 MHz.  You will see black vertical strip
if higher frequency like 7M is enabled.  I wonder that my example may
look like dithering.

I am asking how do you overcome dither problem on any CRT / LCD screen
for VGA monitor while you are running Apple IIgs Emulator.  There is a
way to hide dither by combiing each pair of pixels into solid color
with dithering translation table.