Subject:
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Re: How to dither colors
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Newsgroups:
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lugnet.cad
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Date:
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Thu, 24 Jun 1999 14:31:46 GMT
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Viewed:
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611 times
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Thanks. I knew that was in there but couldn't find it. This section should
be moved to (or at least referenced in) the section on Color Codes.
-John Van
Lars C. Hassing <lch@ccieurope.com> wrote in message
news:57F1FE754246D211A98700805FB7914501BCDE50@aarhus...
> John VanZwieten asked:
> > What's the formula for calculating a dithered color?
> >
> > color 1 * ??? + color 2. What value is ???
>
> The Ldraw FAQ (http://www.ldraw.org/FAQ/) says:
> Colours
> Colours are outlined in LEDIT.DOC. Two special values are 16 and 24.
> 16 is the 'current colour', i.e., whatever colour was specified on
> the type 1 line which caused the current line to be executed.
> Colour 24 is a complementary colour to the current colour, usually
> the bright/dark complementary shade. So if the current colour is
> dark blue, colour 24 would give bright blue.
>
> Also, colours 256 through 511 are dithered. So if you want to
> combine colours J and K, figure your colour value as
>
> colour = (J * 16) + K + 256
>
> The complementary colour of J is used as the complementary colour
> of the dithered value. So you can control the edge colour
> (somewhat) by switching J and K.
>
> <end-quote>
>
> LDraw uses dithering because it only had 16 colors available in
> a VGA display. On modern computers having 65536 or 16 million
> colors, a renderer could choose to blend the rgb color values
> (like L3P does): rgb = (rgb(J)+rgb(K)) / 2
> /Lars
>
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Message is in Reply To:
 | | RE: How to dither colors
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| John VanZwieten asked: (...) The Ldraw FAQ ((URL) says: Colours Colours are outlined in LEDIT.DOC. Two special values are 16 and 24. 16 is the 'current colour', i.e., whatever colour was specified on the type 1 line which caused the current line to (...) (25 years ago, 24-Jun-99, to lugnet.cad)
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