One method would be to use the hue and intensity values of the color to
form the grey scale value of that color, and then render the grey scale
colors.  Perhaps applying a greyscale equation to your pigments?

Steve


Nieminen Mika wrote:
> 
> Ken <tyl### [at] pacbellnet> wrote:
> : Anyway My solutions was of course to use shades of gray for all objects
> : in the scene.
> 
>   How do you model this:
> 
>   Three objects: One is yellow, one is cyan and one is white.
>   Two light sources: One is red and the other is blue.
>   Of course the red light source only illuminates the yellow and the white
> object while the blue light source only illuminates the cyan and also
> the white object.
>   I want this image in b/w.
> 
> --
> main(i,_){for(_?main(i+1,"FhhQHFIJD|FQTITFN]zRFHhhTBFHhhTBFysdB"[--i]
> ):5;i&&_>1;printf("%s",_-70?_&1?"[]":" ":(_=0,"\n")),_/=2);} /*- Warp -*/

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Lance Birch wrote in message <36e8a932.0@news.povray.org>...
>The best way is to convert all the colours in your scene to shades of gray
>using a grayscale algorithm.  You can't currently tell POV-Ray to render to
>greyscale.


Sure you can!
Check out the global-settings option "HF_Gray_16" (it has it's own little
chapter in the docs BTW).



Johannes.

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So it goes...

My answer lingered a bit in the outbox, and when I looked the next time,
Roland had already given the correct answer :-)  - by then my answer was
already posted ...

Johannes.

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Didn't somebody post a POV ray file that converted from RGB to HSB and HSV...
those would probably be most helpful in created a B&W image.


Stephen Lavedas wrote:

> One method would be to use the hue and intensity values of the color to
> form the grey scale value of that color, and then render the grey scale
> colors.  Perhaps applying a greyscale equation to your pigments?
>
> Steve
>
> Nieminen Mika wrote:
> >
> > Ken <tyl### [at] pacbellnet> wrote:
> > : Anyway My solutions was of course to use shades of gray for all objects
> > : in the scene.
> >
> >   How do you model this:
> >
> >   Three objects: One is yellow, one is cyan and one is white.
> >   Two light sources: One is red and the other is blue.
> >   Of course the red light source only illuminates the yellow and the white
> > object while the blue light source only illuminates the cyan and also
> > the white object.
> >   I want this image in b/w.
> >
> > --
> > main(i,_){for(_?main(i+1,"FhhQHFIJD|FQTITFN]zRFHhhTBFHhhTBFysdB"[--i]
> > ):5;i&&_>1;printf("%s",_-70?_&1?"[]":" ":(_=0,"\n")),_/=2);} /*- Warp -*/

--
Josh English
eng### [at] spiritonecom
www.spiritone.com/~english

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Roland Mas wrote:

> I wondered how long it would take until someone would notice this...
> I'm afraid you all lost :-)
> 
> The doc says it all (almost):
> 
> --- Cut here ---
> 7.8.4            HF_Gray_16
> 
> The hf_gray_16 setting is useful when using POV-Ray to generate
> heightfields for use in other POV-Ray scenes. The syntax is...
> 
>   global_settings { hf_gray_16 BOOLEAN }
> 
> The boolean value turns the option on or off. If the keyword is
> specified without the boolean value then the option is turned on. If
> hf_gray_16 is not specified in any global_settings statement in the
> entire scene then the default is off.
> 
> When hf_gray_16 is on, the output file will be in the form of a
> heightfield, with the height at any point being dependent on the
> brightness of the pixel.  The brightness of a pixel is calculated in
> the same way that color images are converted to grayscale images:
> 
>   height = 0.3 * red + 0.59 * green + 0.11 * blue
> 
> Setting the hf_gray_16 option will cause the preview display, if used,
> to be grayscale rather than color. This is to allow you to see how the
> heightfield will look because some file formats store heightfields in
> a way that is difficult to understand afterwards. See section "Height
> Field" for a description of how POV-Ray heightfields are stored for
> each file type.
> --- Cut here ---
> 
> Maybe it should have been a bit clearer.  Anyway, the output can be
> turned into a sixteen bit per pixel black and white image file.  I
> first wrote "at least in Truevision format", but it is not true.  My
> further tests reveal that it works with "PNG" format.  Hence my
> superseding of my previous article.
> 
> Roland.
> --
> Roland Mas
> 

> - Genki desu, ture en zinc.



   For the purposes of the i.r.t.c. contest this method is invalid. Yes it
 is true that the image is in 16 bit gray scale but it is also true that
 if try to view it in a normal image viewing program it is not recognizable
 as a normal image. In most cases they an ugly green in color and highly
 pixelated in appearance. To make it visible it needs to be color and format
 converted. If you are going to do that you might as well use an image
 conversion program to turn into 256 shades of gray and gain the added color
 depth in the process. Either way it's not allowed in the competition so it's
 a moot point. It is for these reasons I did not bring it up before simply
 because it's not the solution the original poster will need to accomplish
 his goal.


-- 
Ken Tyler

mailto://tylereng@pacbell.net

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hf_gray_16 generates 16 bit grayscale images, every pixel value should be
considered a 2-byte "word". This is non-standard; graphics packages will not
translate the image correctly as a grayscale bitmap. Have you looked what a
heightfield tga looks like in, say, PSP? It's red-green.

Margus

Roland Mas wrote in message ...
>
>I wondered how long it would take until someone would notice this...
>I'm afraid you all lost :-)
>
>The doc says it all (almost):
>
>--- Cut here ---
>7.8.4            HF_Gray_16
>

Post a reply to this message

I'm pretty sure that reasonable post processing is allowed in the IRTC.
I recall reading that processing which affects all pixels similarly is
acceptable, ie. 'if you wouldn't be willing to do it to every frame of
an animation, it's probably not acceptable' so I'd just load the image
into a paint program and grey scale it.

Cheers, PoD.

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On 12 Mar 1999 17:38:53 +0100, rol### [at] casimirrezelenstfr (Roland
Mas) wrote:

>I wondered how long it would take until someone would notice this...
>I'm afraid you all lost :-)
>
>The doc says it all (almost):
>
>--- Cut here ---
If you say so... :)
>--- Cut here ---
>
>Maybe it should have been a bit clearer.  Anyway, the output can be
>turned into a sixteen bit per pixel black and white image file.  I
>first wrote "at least in Truevision format", but it is not true.  My
>further tests reveal that it works with "PNG" format.  Hence my
>superseding of my previous article.
>
>Roland.

Use the output image as a source for a height_field turned towards the
camera with a gradient pattern ranging from black to white and
pointing towards the viewer. For example, this

height_field
{
  png "hf16g.png"
  texture
  {
    pigment { gradient y color_map { [0 color rgb 0][1 color rgb 1] }}
    finish { ambient 1 }
  }
  translate -0.5
  scale <1,1/1000,1>
  rotate -90*x
}

camera
{
  location -2*z
  up y
  right x
  angle 30
  look_at 0
  orthographic
}

should work, imho. Use the same output file width and height settings
as for the original, color image.

---------
Peter Popov
ICQ: 15002700

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Damn! You beat me to it. Perhaps I should write my messages online.

Margus

Ken wrote in message <36E96D77.9FBEB7EF@pacbell.net>...
>
>   For the purposes of the i.r.t.c. contest this method is invalid. Yes it
> is true that the image is in 16 bit gray scale but it is also true that
> if try to view it in a normal image viewing program it is not recognizable
> as a normal image. In most cases they an ugly green in color and highly
> pixelated in appearance. To make it visible it needs to be color and
format
> converted. If you are going to do that you might as well use an image
> conversion program to turn into 256 shades of gray and gain the added
color
> depth in the process. Either way it's not allowed in the competition so
it's
> a moot point. It is for these reasons I did not bring it up before simply
> because it's not the solution the original poster will need to accomplish
> his goal.
>
>
>--
>Ken Tyler
>
>mailto://tylereng@pacbell.net

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On Fri, 12 Mar 1999 11:39:35 -0800, Ken <tyl### [at] pacbellnet> wrote:
>   For the purposes of the i.r.t.c. contest this method is invalid. Yes it
> is true that the image is in 16 bit gray scale but it is also true that
> if try to view it in a normal image viewing program it is not recognizable
> as a normal image. 

This is only true if you output to a TGA image.  PNG and PPM both output
as plain grays.

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