.oO C=64 colors Oo. (fwd)

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.oO C=64 colors Oo. (fwd)

Marko Mäkelä-2
Hello all!

I don't have time for the following stuff, but hopefully some of you can
cooperate with this guy.  I'm not sure whether his point regarding the
methods used for extracting the RGB values is valid.  In order to measure
the RGB values, you have to extract the information from the chroma
signal, and every method doing so may be inaccurate.

See also my luminance level measurements at
<URL:http://www.funet.fi/pub/cbm/documents/chipdata/656x-luminances.txt>
if you are interested in this topic.  Also, Pasi Ojala, George Taylor (are
you on this list?) and another NTSC guy made some color measurements at
about the same time I measured the luminances at the end of 1996 (gosh,
the time flies: I thought it would've been at the end of 1997).

        Marko
---------- Forwarded message ----------
Date: Sun, 24 Jan 1999 21:14:16 +0100
From: Philip Timmermann <[hidden email]>
To: [hidden email]
Subject: .oO C=64 colors Oo.

Hola...

I  already  sent  the  following mail a few hours ago, but my provider
replied me a message, that your account doesn't exist...

I'm trying again now... hope you don't get this several times... 8-/

-///-CUT-HERE---------------------------------------------------------

Hola...

First of all, please excuse my really bad english - it's not my native
language, but i hope all is 'understandable'...  ;)

I  read  your  Name  in various Articles about the VIC-II and therefor
hope, that you are the right man in the right place...  ;-)

Since  quite  some time, I'm studying the color-palette of my C=64 and
searched a 24bit-equal (RGB) in the first place, in order to work with
it on my Amiga...

After  collecting and studying many Palettes, i recognized that no one
really matched the original C=64 colors...

No  palette for example 'took care' of the fact that every color has a
'partner-color'  with  exactly  the  same  brightness  (at least on my
C=64_c).   This  can  be  quite easily verified, by removing the color
with  the slider of the C=64-Monitor.  Someone informed me via e-Mail,
that  the  C=64_a differs in color-behaviour and brightness within the
palette...   Theoretically  this can also be verified, by removing the
color on the monitor...
                                             .---+-------------+-----.
Here  is  a list, in which you can see, how  !<b>!     64a     ! 64c !
the colors are sorted by brightness.  "<b>"  +---+-------------+-----+
is  the  brightness, where 0 is the darkest  ! 0 ! 0           ! 0   !
and 8 is the brightest.  The numbers on the  ! 1 !             ! 6,9 !
right  are  Hex-Codes  of the colors in the  ! 2 ! 2,6,9,B     ! 2,B !
C=64-palette.   The  numbers  of the C=64_a  ! 3 !             ! 4,8 !
are by a guy from Usenet...                  ! 4 ! 4,5,8,A,C,E ! C,E !
                                             ! 5 !             ! 5,A !
                                             ! 6 ! 3,7,D,F     ! 3,F !
Following   here,   is   a   list   of  the  ! 7 !             ! 7,D !
color-names  which  belong to the Hex-codes  ! 8 ! 1           ! 1   !
of the palette...                            +---+-------------+-----+

.---+------------+---+------------+---+------------+---+-------------.
! # ! color-name ! # ! color-name ! # ! color-name ! # ! color-name  !
+---+------------+---+------------+---+------------+---+-------------+
! 0 ! Black      ! 4 ! Purple     ! 8 ! Orange     ! C ! Medium-Grey !
! 1 ! White      ! 5 ! Green      ! 9 ! Brown      ! D ! Light-Green !
! 2 ! Red        ! 6 ! Blue       ! A ! Light-Red  ! E ! Light-Blue  !
! 3 ! Cyan       ! 7 ! Yellow     ! B ! Dark-Grey  ! F ! Light-Grey  !
+---+------------+---+------------+---+------------+---+-------------+

Info:   It's  not  'getting  brighter' in a linear way...  (C64_c) The
'Jump' between the color-pair C-E and 5-A is for example shorter, than
the 'Jump' between the other color-pairs, and the 'Jump' between 0 and
the  color-pair 6-9 or between 1 and the color-pair 7-D is bigger than
the other 'Jumps'...

Additionally  the  Greys  can  _not_  (!)  be 'build' by simple logic:
Dark-Grey    (64/64/64),    Medium-Grey    (127/127/127),   Light-Grey
(191/191/191)...    That's  _not_  the  way  it  works...   Dark-  and
Light-Grey are much 'closer' to Medium-Grey, than to BLK or WHT...

"Removing  the  color  with mon-slider" can be precisely emulated with
lots  of  Image-Processor-Prgs.  The program PPaint (Amiga) by Cloanto
for  example  features  a  color-intensity-slider,  with which you can
slowly  fade  out the color.  I tested, if this digital method differs
from  the  analog  method of the monitor.  I connected an Amiga to the
same  monitor like the C=64 and displayed a very colorful picture with
PPaint.   Then  I  moved  the color-intensity-slider of PPaint and the
change  was of course very visible.  Then I removed the color with the
slider  of  the  monitor and again moved the color-intensity-slider of
ppaint.   No  change  was visible at all, so i think that both methods
deliver the very same results.

So  you can easily verify if a RGB-color-clone of the palette features
the same color-brightness of the original.

No  RGB-clone  I  found  was sucessful in this test.  Most people just
made  'Full-Range'-palettes  (Red  (FF/00/00),  Blu (00/00/FF), etc.).
Some  people  tried  to  match  the  color  by placing a PeeCee with a
MultiScan-Mon  next  to  the  C=64  with C=64-mon and do it 'by hand'.
These  palettes  differ  much  from  the  original, because it heavily
depends on Color-, Contrast- and Brightness-settings of the C=64-mon.

Additionally  there are palettes from people, who just connected their
C=64  to  a  TV-card or a FrameGrabber in order to digitize the color.
Sadly  every  TV-card  and  FrameGrabber  seems  to  have  a different
color-behaviour, so all these palettes differ very much from eachother
and aren't sucessful in the PPaint-test...

Sooooo,  there  must be a possibility to get the _exact_ and _precise_
24  Bit  RGB-Values...   Theoretically it must be possible to find the
color-values which the VIC-II really produces...

Sadly  I'm  no  hardware-specialist at all, but you seem to know a lot
about  the  VIC-II, and even if you don't have the needed hardware you
perhaps  know some friends who have!?  I guess you are one of the last
people who can solve one of the last misterys of the C=64...  8^)

I  would  like  to  know  what you think about all this and if you can
think of a method which could help to find the right values...

Thanks  for  your  time...  C= forever...  ;-) can't wait to read your
reply!  Please let me know, if this mail reached you...

.oO Philip 'Pepto' Timmermann Oo.

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