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Gordon wrote:
>
> Jerry Anning wrote in message <36e98f24.23757454@news.povray.org>...
> >On Sat, 13 Mar 1999 06:44:16 +1030, PoD <pod### [at] merlin netau> wrote:
> >
> >>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.
> >
> >Not so, I'm afraid. That would definitely be illegal postprocessing.
> >The intent of the rule and the somewhat poor example you quote has
> >been clarified in irtc-l. The desired situation is no postprocessing
> >at all. About the only things generally considered acceptable
> >postprocessing are: adding copyright/sig, jpeg conversion. resizing,
> >gamma/brightness correction, (this causes some controversy) stitching
> >together an image rendered in pieces and (this is even more
> >controversial) cropping in certain circumstances. Many people go to
> >great extremes to avoid even these things where possible.
> >
> >Jerry Anning
> >clem "at" dhol "dot" com
>
> While I haven't had a go at IRTC (yet), I have read the rules. It seems to
> me that it is quite acceptable to use a graphics program to convert an image
> from one "file format" to another, for axample, TGA to JPG, for posting. How
> is it different if I open my 16-bit grayscale image and save it as a 24-bit
> jpeg? The program recognises that the image is gray, not colour and behaves
> appropriately.
>
> Comments?
>
> Gordon
> <gbe### [at] birdcameroncomau>
I think in this case it is more an issue of taking a 16m color image
and converting it to 256 shades of gray that would be in non compliance
with the rules. If you are silly enough to take make a rendering in Pov's
16bit greyscale, convert it, and then submit it to the competition you
might just get sympathy votes for being so stupid.
--
Ken Tyler
mailto://tylereng@pacbell.net
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Gee!!! I've used that thing HUNDREDS of times and yet I've totally
forgotten it existed!!! he he he
And of course, that's right, you'd think that after studying physics for 6
months and a huge chapter on colour wavelengths I would have realised that
you can't just use an algorithm to convert the pigments in your scene
because then the lights won't react in the right way!!!
Maybe I should actually consider THINKING before I post!!!
--
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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OK, I've got an idea but I can't remember if it's possible or not (it's been
a while since I've used POV-Ray).
Can you render the image in normal colour, then SOMEHOW work out a way of
rendering the two images over each other with negative colour indices? That
way the resulting image would be black and white...
The only problem is, how do you get an inverse of the picture without doing
image editing? Is there a way to multiply the image_map pigments by -1?
This would solve all the problems, if it were possible. Any ideas?
Of course the other way (WHICH WOULD TAKE MUCH LONGER!!!) is to write a
macro which reads from the Targa file and creates an array of boxes with the
black and white colour conversions for each pixel so that when rendered you
would have the image again... You'd have to turn anti-aliasing off...
--
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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Lance Birch wrote:
>
> OK, I've got an idea but I can't remember if it's possible or not (it's been
> a while since I've used POV-Ray).
>
> Can you render the image in normal colour, then SOMEHOW work out a way of
> rendering the two images over each other with negative colour indices? That
> way the resulting image would be black and white...
>
> The only problem is, how do you get an inverse of the picture without doing
> image editing? Is there a way to multiply the image_map pigments by -1?
>
> This would solve all the problems, if it were possible. Any ideas?
>
> Of course the other way (WHICH WOULD TAKE MUCH LONGER!!!) is to write a
> macro which reads from the Targa file and creates an array of boxes with the
> black and white colour conversions for each pixel so that when rendered you
> would have the image again... You'd have to turn anti-aliasing off...
>
> --
> Lance.
I don't know why anybody would go through the trouble. It is very easy
to make grey scale images without resorting to a bunch of tricks or having
to use post processing techniques. Grey/Gray is an easy color to specifiy
in Pov and will work with any pigment pattertn and texture types. It really
is not that difficult to choose the right colors. I have more trouble getting
the right shades of colors than I do shades of grey and I'm pretty good at
color control.
--
Ken Tyler
mailto://tylereng@pacbell.net
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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
See what a mess you started here Kyle ?
One other possibility that the folks in this crowd can grind donw the
merit of is using a reflection vector with every object in the scene.
If you use reflection <0.5,0.5,0.5> the color reflected off the object
will by a 50% gray and the rest will be filtered out. How well this
would work is untested and I don't know if you can stack reflection
vectors on top of each other. If you can it might be possible to make
a global reflection for the whole scene. Or - maybe not !
--
Ken Tyler
mailto://tylereng@pacbell.net
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NO NO NO!!! It DOESN'T WORK!!!
Ken, have you tried a red light source on a red and white sphere lately?
I'd like you to try making that in greyscale... This is the point I missed
in my first post and I really should have pointed it out earlier. Remember,
because the light sources can be different colours, the surfaces of objects
will react in different ways. Like a blue shere will look different under
red light... and another coloured sphere under the same light will look
different again. If you convert the lights to just intenisties (which is
what you're suggesting) the surfaces won't react differently so the objects
won't appear realistic.
Remember, the problem lies in the wavelengths.
--
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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Hi everyone, thanks for the great response to my post. Well, I've read
through all of them and I've come to the conclusion that there is NOT an
automatic way to do this in POV-Ray. My goal was for my image to look
like an old B&W photo, old west style particularly. I guess it seems to
me that the only real way to do it is to do what Ken said and just give
each object a grey color. I haven't actually tried it yet so I don't
know how hard it will be. Actually, I think it may give me some very
badly needed control over my colors and textures (I can never seem to
get them quite right). I'll have a go at it and post my creation in
binaries.images when I'm done. Well, here goes nothin'.
Once again, thanks everyone for racking your brains trying to think of a
solution. I really appreciate it.
Kyle
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
>
> See what a mess you started here Kyle ?
>
> One other possibility that the folks in this crowd can grind donw the
> merit of is using a reflection vector with every object in the scene.
> If you use reflection <0.5,0.5,0.5> the color reflected off the object
> will by a 50% gray and the rest will be filtered out. How well this
> would work is untested and I don't know if you can stack reflection
> vectors on top of each other. If you can it might be possible to make
> a global reflection for the whole scene. Or - maybe not !
>
> --
> Ken Tyler
>
> mailto://tylereng@pacbell.net
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Lance Birch wrote:
>
> NO NO NO!!! It DOESN'T WORK!!!
>
> Ken, have you tried a red light source on a red and white sphere lately?
> I'd like you to try making that in greyscale... This is the point I missed
> in my first post and I really should have pointed it out earlier. Remember,
> because the light sources can be different colours, the surfaces of objects
> will react in different ways. Like a blue shere will look different under
> red light... and another coloured sphere under the same light will look
> different again. If you convert the lights to just intenisties (which is
> what you're suggesting) the surfaces won't react differently so the objects
> won't appear realistic.
>
> Remember, the problem lies in the wavelengths.
>
> --
> Lance.
YES YES YES ! IT DOES TOO WORK !!!!!
By my will,
My will alone,
I set my mind in motion...
Grey is grey is grey is grey and you can't turn it red or blue in a
grey world.
It's the artistic interpretation of the colors applied to the medium
that will make it work and the physics of are not important to the the
minds interpretation of the colors. If I have an object I want colored
a certain way THAT is physical reality. If I have to match the grey
colors in a black and white photo then there may be an issue but only
if I choose to make an issue out of it. Fact is with art you don't
have to care about physical reality. Show me a painting by one of
the "Masters" that really looks like a 3D human were standing there.
I have yet to see one.
Get my point or should I rationalize it a bit more for you ?
--
Ken Tyler
mailto://tylereng@pacbell.net
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I hate to tell this to you Mr Tyler but this is one time that I AM RIGHT!
I want you to replicate this for me in greyscale... using your so-called
"rationalisations".
You have a yellow sphere, a red light to the left, a blue light to the
right. The result after rendering and conversion to greyscale is NOT the
same as converting the colours to intesities and then rendering.
Do you want me to prove it with pictures?
--
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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I hate to tell you this but Ken is wrong, the result CANNOT be the same.
For example, if you have a yellow sphere, a red light to the left, a blue
light to the right, after rendering and converting to greyscale the result
with NOT be the same as converting the colours to grey first and then
rendering. (As the converted lights will not react the same way with the
objects because they no longer obey colour laws of wavelength, they all have
mono-wavelengths)
--
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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