| Re: Help with moving from 8 to 24 bit colour [message #17190 is a reply to message #17189] |
Thu, 23 September 1999 00:00   |
jeyadev
Messages: 78
Registered: February 1995
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Member |
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In article <MPG.12533f6852f3ee22989906@news.frii.com>,
David Fanning <davidf@dfanning.com> wrote:
> Surendar Jeyadev (jeyadev@wrc.xerox.com) writes:
>
>> After some messing around, I found that the solution is as follows:
>>
>> device, pseudo_color=8
>>
>> I am not sure what this does (that is part of today's education!),
>
> What this does is make your expensive new hardware act
> like it was last year's model. :-)
>
> But, I agree, this will solve all of your problems and
> you can carry on like you have been.
Yes, I recognized that that is what it would do. But, it was done
in the interest of time. I am still learning ...
> Should you ever have the need or desire to see more
> than 256 colors simultaneously, however, I recommend
> you use the TrueColor visual class and not the
> DirectColor visual class, which appears to be the
> default for your machine. DirectColor confuses all
> of us. :-)
Glad to know that even you are confused by this. The trouble is
that I cannot find a self contained book that can help. Being
sent off to learn about X windows and its graphical libraries
to do a reasonably simple analysis is too much! But, I will
continue to bite away ...`
> In a PseudoColor visual class you specify a color by
> specifying an index into a color table. Suppose, for
> example, we load the color yellow into color index
> 10 of the color table. Yellow is full red and full
> green, but no blue. We could load those values in
> the current color table like this:
>
> TVLCT, 255, 255, 0, 10
>
> To draw a plot in that yellow color, we would do this:
>
> Plot, data, Color=10
>
> We have specified the color as an *index* into the color
> table. If we load a new color into index 10, then the
> graphic display is automatically updated, since the
> display is "tied to" or "connected to" the index.
I remember this from the SunView to OpenWindows transition. In
those Good Old Days, Sun actually sent reasonable verbose
hard copy documentation explaining how all this worked! I
actually learnt something!!
> If we want a yellow color in a 24-bit environment, we
> don't use an index, but we specify the color directly.
> .....
Thanks a lot for this bit. But, guess what? I have a new
question for you.
I have long been interested in getting your book to step
beyond my "plain graph" skills with PV Wave. Is this kind
of thing written up there (see my earlier complaint above!)?
I guess I will buy it anyway!!
thanks, again
sj
--
Surendar Jeyadev jeyadev@wrc.xerox.com
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