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Re: RGB colors
Linards Ticmanis wrote:
Knut wrote:
BTW I'm also wondering a bit on the colors they change with this RGB
output being more normal (comparing with other computers). I have now
seen the NTSC colors which BTW is quite a bit stronger than the PAL
ones. How are the IIc and IIgs RGB, do they represent the colors like
the original II or like my IIe RGB card?
Probably the latter, have a look at the KEGS emulator, according to the
source code it uses the same RGB values for the old Apple colors as a
real IIgs, and it's colors are definitely more saturated and also
different in tone than those of the Apple's composite output.
Actually no, to me KEGS does the colors more like NTSC. Maybe there is a
kind of saturation difference which I think is not possible with RGB
colorspace (would have to be YUV colorspace).
What I mean is that the "NTSC color" Brown (color number 8) comes out as
dark grey while grey 1 (#5) comes out as brown (or dark yellow).
Actually I find that the CGA monitor has a quirk there with the number 5
color, brown has distinctly more red than green interpolated with the
rest of the colors it would have the RGB values R=170, G=170, B=0 but I
think what I found on the net 170, 85, 0 is correct. All colors except
brown are regular R,G,B gives 170 on the respective R,G,B while
intensity adds 85 to all three (170+85=255 and 0+85=85). (0=0/3, 85=1/3,
170=2/3 and 255=3/3...)
I wonder how the real AppleColor 100 monitor displays the colors... Does
anyone know how the "summing network" in the AppleColor 100 monitor is?
There is also another difference with the RGB card, I get color in RGB
in some situations that is white on NTSC and I et white in some
situations that is colored on NTSC. For example. On the test/demo disks
for that RGB card 'Apple Extended 80-Column Text - AppleColor Card Demo,
The' I got from the net. ProDos side (2of2) 'DHR COLORS' display the
text except the title is white while on NTSC it is really mixed up
colors. DOS3.3 side (1of2) on RGB the startup logo is colored in stripes
like the real logo while on NTSC it is white. Obviously this is not same
as the original II. How does it fit with IIc and IIgs. The emulators
does same as NTSC (text is unreadable). I now realize that IIgs might be
more compatible in this regard than a IIe with RGB.
This is what the 'DHR COLORS' looks like on CGA (I found that I could
not take a satisfactory photo so this is a drawing, that is very similar
to what I see).
http://home.online.no/~kr-lund/AppleColor-CGA.png
This is the same grabbed from the Kegs emulator and looks much like
NTSC, but on NTSC it is easier to read the text.
http://home.online.no/~kr-lund/AppleColor-KEGS.png
Here is an NTSC frame grab of the same, note that the framegrabber isn't
that good and adds both general noise, sampling noise and conversion
noise (YUV to RGB). But you can see that here the text, although
colored, is readable. I think the fringes are from the YUV to RGB
conversion.
http://home.online.no/~kr-lund/AppleColor-NTSC.png
I think that this difference in the emulated colored text pixels and
NTSC is because what is a colored quad "pixel" in RGB is in YUV space
and you get a Y component (luminance) that corresponds to the white
pixel (of RGB) while UV (Chrominance) covers the quad. I think the
emulators aren't doing this right...
Knut