Hi everyone.  I have a quick question.  Is there any way to have POV-Ray
render in black and white?  I'm thinking about submitting an IRTC image
in black and white, but since post-processing is not allowed, I don't
see a good way to do it.  Is there some setting in POV-Ray for this?  Of
course, I can just give all the objects a greyish color but I don't
think that would come out very nicely.  Well, if anyone has a suggestion
I'd be very grateful to hear it.

		Kyle

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Kyle wrote:
> 
> Hi everyone.  I have a quick question.  Is there any way to have POV-Ray
> render in black and white?  I'm thinking about submitting an IRTC image
> in black and white, but since post-processing is not allowed, I don't
> see a good way to do it.  Is there some setting in POV-Ray for this?  Of
> course, I can just give all the objects a greyish color but I don't
> think that would come out very nicely.  Well, if anyone has a suggestion
> I'd be very grateful to hear it.
> 
>                 Kyle

  I did an image I think last December that was titled I believe "Black
and White Povatography". It is in the images group. In that I explored the
wonderful world of black and white photography as represented in a raytracing
program that is commonly used for color image production. Anyway My solutions
was of course to use shades of gray for all objects in the scene. It's really
not that difficult to do since all of your pigments can be designed using a
single rgb float value - pigment{rgb .5} would be 50% gray for example.
The most difficult part is choosing the correct finish statements and lighting
models to get the same sharp contrast that b/w photos are famous for. Getting
sharp shadows is a trademark item for b/w photos that I had trouble recreating.
I think there is a certain limitation in the represention of b/w images on
an electronic medium but that is a nother story.
 As far as special settings for Pov I know of no setting that will allow a
256 shades of grey pallet or display output as used as the standard for
electronic b/w image reproduction.



-- 
Ken Tyler

mailto://tylereng@pacbell.net

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I also did a B&W image merely by using only shades of grey in my image.
You might also consider a brownish image by using a filter.  My image is
in the Element's round of the IRTC and is titled DarkLight.

Steve


Ken wrote:
> 
> Kyle wrote:
> >
> > Hi everyone.  I have a quick question.  Is there any way to have POV-Ray
> > render in black and white?  I'm thinking about submitting an IRTC image
> > in black and white, but since post-processing is not allowed, I don't
> > see a good way to do it.  Is there some setting in POV-Ray for this?  Of
> > course, I can just give all the objects a greyish color but I don't
> > think that would come out very nicely.  Well, if anyone has a suggestion
> > I'd be very grateful to hear it.
> >
> >                 Kyle
> 
>   I did an image I think last December that was titled I believe "Black
> and White Povatography". It is in the images group. In that I explored the
> wonderful world of black and white photography as represented in a raytracing
> program that is commonly used for color image production. Anyway My solutions
> was of course to use shades of gray for all objects in the scene. It's really
> not that difficult to do since all of your pigments can be designed using a
> single rgb float value - pigment{rgb .5} would be 50% gray for example.
> The most difficult part is choosing the correct finish statements and lighting
> models to get the same sharp contrast that b/w photos are famous for. Getting
> sharp shadows is a trademark item for b/w photos that I had trouble recreating.
> I think there is a certain limitation in the represention of b/w images on
> an electronic medium but that is a nother story.
>  As far as special settings for Pov I know of no setting that will allow a
> 256 shades of grey pallet or display output as used as the standard for
> electronic b/w image reproduction.
> 
> --
> Ken Tyler
> 
> mailto://tylereng@pacbell.net

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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.

--
Lance.


---
For the latest 3D Studio MAX plug-ins, images and much more, go to:
The Zone - http://come.to/the.zone

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Using a filter? Please elaborate. I'd like to know how you do this.

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Richard Speir wrote:
> 
> Using a filter? Please elaborate. I'd like to know how you do this.

A simple way would be to use something like a box in front of the camera
with a filtering pigment. Only certain colors owuld be allowed to pass
while others would be blocked. If you use several layers of pigments
you can greatly lower the bands of permissable colors allowed to pass.

I'm not sure if this is what he had in mind but it will work to some extent.

-- 
Ken Tyler

mailto://tylereng@pacbell.net

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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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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 -*/

If you really want this so badly I suggest...

-- 
Ken Tyler

mailto://tylereng@pacbell.net

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Nieminen Mika <war### [at] cctutfi> writes:

>   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.

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 is (at
least in Targa Truevision format) a sixteen bit per pixel black and
white image file.

Roland.
-- 
Roland Mas


- Genki desu, ture en zinc.

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Nieminen Mika <war### [at] cctutfi> writes:

>   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.

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.

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