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Re: IDL and 24 Bits--help + added question [message #2210 is a reply to message #2208]

Wed, 22 June 1994 06:22

velt
Messages: 19
Registered: June 1994

Junior Member

In article 45v@mother.usf.edu, velt@rad.usf.edu (Robert Velthuizen) writes:
> In article 772209127@imsy1.nrl.navy.mil, grunes@imsy1.nrl.navy.mil (Mitchell R Grunes) writes:
>> In article <PWALKER.94Jun20165914@jean-luc.ncsa.uiuc.edu> pwalker@ncsa.uiuc.edu (Paul Walker) writes:
> <stuff on pseudo-color on true-color visual deleted>
>> ----------NOW FOR MY QUESTION----------
>>
>> Actually, I have been trying to find a way to simulate 24 bit color for
>> TV commands on 8 bit color displays (e.g., Sun, VGA...I think it could
>> be done with some fancy dithering, but I don't want to do it). Does
>> anyone have (or know of) a routine to do it?
>> Mitchell R Grunes (grunes@imsy1.nrl.navy.mil)
>> Allied-Signal Technical Services
>> c/o Code 7230 Naval Research Lab
>>
>
> I don't think there are ready-made programs in IDL to do it. In the documentation
> for John Bradley's xv there is mention of
> "... ppmquant, written by Jef Poskanzer. This algorithm also uses
> a version of Heckbert's median cut algorithm, but is capable of
> picking 'better' colors, and it doesn't dither."
> This may be an algorithm you want to look into.
>
> Good Luck,
> Robert Velthuizen
> Digital Medical Imaging Program of the
> H. Lee Moffitt Cancer Center and Research Institute at the
> University of South Florida.
>

I received a reply from David Stern of RSI:
>> Bob:
>>
>> Try the COLOR_QUAN function. It does a very good of quantizing 24
>> bit image into pseudocolor images of <= 256 colors. It will also do
>> optional dithering etc. Often, the images look just as good as their
>> 24 bit counterpart. You can also use it to combine data sets.
>>
>> Hope this helps,
>> David
>>

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[Message index]

		Re: IDL and 24 Bits--help + added question By: grunes on Wed, 22 June 1994 08:16
		Re: IDL and 24 Bits--help + added question By: velt on Wed, 22 June 1994 06:22
		Re: IDL and 24 Bits--help + added question By: thompson on Wed, 22 June 1994 06:04
		Re: IDL and 24 Bits--help + added question By: velt on Tue, 21 June 1994 10:07
		Re: IDL and 24 Bits--help + added question By: grunes on Tue, 21 June 1994 07:32
		Re: IDL and 24 Bits--help + added question By: rmm on Fri, 24 June 1994 08:30

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