I'm also looking for a thread that I can't find: it was one where somebody
posted formulas for a conical pattern plus some other stuff.

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Would that be using different "weights" for different colors, i.e., a picture using
only solid rgb would have different gray levels? A very easy way to do it, of
course, would just be to average the rgb values, but somehow I don't think that's
what you want. Then there's hue-chroma-value (referred to as
hue-brightness-saturation in most programs), which would make more sense. I don't
know those, but they should be easy formulas to find.

Remco de Korte wrote:

> There was a discussion in one of the groups on this server not long ago about
> converting rgb to grayscale values. I've been looking for that thread but can't
> find it. Some formulas were mentioned and I'd like to try those again.
>
> Houdoe!
>
> Remco

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Remco de Korte wrote:
> 
> There was a discussion in one of the groups on this server not long ago about
> converting rgb to grayscale values. I've been looking for that thread but can't
> find it. Some formulas were mentioned and I'd like to try those again.
> 
> Houdoe!
> 
> Remco

    Subject: Rendering in B&W?
       Date: Thu, 11 Mar 1999 20:54:19 -0500
       From: Kyle <joe### [at] geocitiescom>
 Newsgroups: povray.general

-- 
Ken Tyler
1100+ Povray, Graphics, 3D Rendering, and Raytracing Links:
http://home.pacbell.net/tylereng/index.html

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Ken wrote:

> Remco de Korte wrote:
> >
> > There was a discussion in one of the groups on this server not long ago about
> > converting rgb to grayscale values. I've been looking for that thread but can't
> > find it. Some formulas were mentioned and I'd like to try those again.
> >
> > Houdoe!
> >
> > Remco
>
>     Subject: Rendering in B&W?
>        Date: Thu, 11 Mar 1999 20:54:19 -0500
>        From: Kyle <joe### [at] geocitiescom>
>  Newsgroups: povray.general

Also:

    Subject:            Rendering Black and White
    Newsgroups:      povray.binaries.images
    Date:                Thu, 05 Aug 1999 07:45:00 -0800
    From:                David Heys <cel### [at] hotmailcom>

David

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On Wed, 29 Sep 1999 04:14:50 +0200, Remco de Korte
<rem### [at] xs4allnl> wrote:

>There was a discussion in one of the groups on this server not long ago about
>converting rgb to grayscale values. I've been looking for that thread but can't
>find it. Some formulas were mentioned and I'd like to try those again.
>
>Houdoe!
>
>Remco

A rough formula is:

Gray = 0.30*Red + 0.59*Green + 0.11*Blue

It might be 31 for red and 10 for blue but you have the idea.

There is a DOS interrupt that would convert a VGA palette entry from
rgb to grayscale. I think it is int 10,10,0b but I might be wrong (man
was it a long ago!). If you have some info on he ints you might check
it out, this is where I know this formula from.


Peter Popov
ICQ: 15002700

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>        Date: Thu, 11 Mar 1999 20:54:19 -0500

YYEEEEYYYY!!!

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Peter Popov wrote:
> 
> A rough formula is:
> 
> Gray = 0.30*Red + 0.59*Green + 0.11*Blue
> 
> It might be 31 for red and 10 for blue but you have the idea.
> 
> There is a DOS interrupt that would convert a VGA palette entry from
> rgb to grayscale. I think it is int 10,10,0b but I might be wrong (man
> was it a long ago!). If you have some info on he ints you might check
> it out, this is where I know this formula from.
> 
> Peter Popov
> ICQ: 15002700

Thanks, for all the replies.
The thread in March wasn't the one because I remembered it as being within the
last three months so it was probably that from August, but what Peter has here
should keep me happy for a while.
BTW: I'm truly very sorry that I can't show you what this is all about, since
it's a project I'm working on that is now close to 200Mb. Just let me say that
it is great fun and nearly 100% POV-Ray on the outside 8)

Remco

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Peter Popov wrote in message ...
>On Wed, 29 Sep 1999 04:14:50 +0200, Remco de Korte
><rem### [at] xs4allnl> wrote:
>
>>There was a discussion in one of the groups on this server not long ago
about
>>converting rgb to grayscale values. I've been looking for that thread but
can't
>>find it. Some formulas were mentioned and I'd like to try those again.
>>
>>Houdoe!
>>
>>Remco
>
>A rough formula is:
>
>Gray = 0.30*Red + 0.59*Green + 0.11*Blue
>
>It might be 31 for red and 10 for blue but you have the idea.
>
>There is a DOS interrupt that would convert a VGA palette entry from
>rgb to grayscale. I think it is int 10,10,0b but I might be wrong (man
>was it a long ago!). If you have some info on he ints you might check
>it out, this is where I know this formula from.


The interrupt is INT 10 with AX = 101B.  The list I have doesn't have any
more information than that.

Mark

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On Thu, 30 Sep 1999 00:29:58 -0400, "Mark Wagner"
<mar### [at] gtenet> wrote:

>The interrupt is INT 10 with AX = 101B.  The list I have doesn't have any
>more information than that.
>
>Mark

I just checked the Norton Guide to see if my numbers were correct (I
had some doubts they were 0.31, 0.59, 0.10 instead but they are the
way I reviously posted them) and I saw that indeed the subfunction was
1B. Well, I haven't played with the VGA since I got windoze 95 (4
years now?)

Anyway, enough OT. I just wanted to say that I checked with my sources
and confirm the formula 0.30*R + 0.59*G + 0.11*B.


Peter Popov
ICQ: 15002700

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Peter Popov <pet### [at] usanet> wrote in message
news:6WXzNyMAeFLWgFeK1pOv0qUCHWEV@4ax.com...
[snip]
>
> Anyway, enough OT. I just wanted to say that I checked with my sources
> and confirm the formula 0.30*R + 0.59*G + 0.11*B.

Is your source the POV documentation? ;-) Because in that awesome and
mightily complete document, you can find the same formula: 0.3 * red + 0.59
* green + 0.11 * blue   :c)

Johannes.

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