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UH-OH....The challenge has been issued....the stakes are high....what'll
happen next in this high drama matchup between 2 leading POV-Ray
superpowers??? Stay tuned to find out....
Kyle
Lance Birch wrote:
>
> 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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Oh don't worry, I realized that early on. I'm only planning on using
one white light anyway. If I do happen to add more they will definately
be white also. That would be WAY too hard to try to compensate for
different light colors and probably far out of my league as well.
Kyle
Lance Birch wrote:
>
> 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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:) Yes, especially considering it isn't possible ;-)
Come on Ken, show your face! Do you want me to prove it?
(I never back down from a wavelength challenge!!! ;-)
--
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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After repeated taunting by Lance, Ken has yet to respond. Has he given
up? Has he admitted defeat? Or does Ken have an ace up his sleeve?
What'll happen next? Don't touch that dial kids!!
Kyle
Lance Birch wrote:
>
> :) Yes, especially considering it isn't possible ;-)
>
> Come on Ken, show your face! Do you want me to prove it?
>
> (I never back down from a wavelength challenge!!! ;-)
>
> --
> 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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By the way Ken, if you are planning on coming up with some strange excuse, I
already have the images that will prove my theory correct! BA HA HA HA!!!
;-)
(And now, for a commercial break)
--
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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In any case, I've just been chatting with Peter and I think it's important
that I draw attention to his post of 13/03/99 6:12 where he has a final
solution to all these problems :)
--
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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#macro m_RGB2G(fRed,fGreen,fBlue)
#local G = 0.3 * fRed + 0.59 * fGreen + 0.11 * fBlue;
(G)
#end
Satisfied folks ? That's the greyscaling algorithm for a colour, apply this to
every colour in the scene, and thereyago, BW image.
Ken be free to use this :-)
Kyle haven't tried the hf_grey_16 yet...
Peter Alternate solution?
Others Whooa...
--
//Spider
( spi### [at] bahnhof se ) [ http://www.bahnhof.se/~spider/ ]
#declare life = rand(seed(42))*sqrt(-1);
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Um, yes... but you won't get the same result...
OK, I think I should stop bothering everyone after this... But I just want
to prove a little point first:
You CANNOT get the same effect of converting and image to greyscale later by
colouring the objects in your scene with greyscale equivalents. It doesn't
work.
The reason is simple and I won't go on about it after this :)
If you plan to have only white lights in your scene, fine, it doesn't make
ANY difference (except for reflections) if you convert a colour image to
greyscale, or if you build your scene with the greyscale equivalents.
However, if you are going to use coloured lights, things get tricky. The
reason it won't work properly is because different colours react in
different ways on other colours. For example, the highlight or specular on
an object will look like it has a different exposure. A good example is to
place a yellow sphere with a red light on one side and a blue light on the
other. If you examine the highlights you'll find that the one produced by
the red light will be exposed more than the one from the blue light. Now if
you were to convert your scene's colours to greyscale before rendering, this
effect isn't produced because you now only have intensities, so all the
highlights will have a linear progression of magnitude. This means that you
can no longer produce scenes with realistic lighting (or reflections), and
that's why it is VERY hard to get the right contrast in a B&W scene if
you're going to make it by using intensities. See? So, ultimately, Peter's
solutions is the ONLY REAL solution to the problem, because that way you are
ACTUALLY rendering the colour, but it is being converted to greyscale later
(well, not later, still in POV-Ray) using the HF16G option, and then
converted to RGB still using POV-Ray by making a height_field from the
resulting PNG image and then colouring the height_field with a gradient from
black to white.
(Did anyone understand my point?)
OK, I'll shut up now...
--
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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To support Roland I have assembled a little example and posted it in
povray.binaries.images.
It shows that B/W rendering is *totally* possible directly from POV-Ray
without any postprocessing that would violate the IRTC rules.
Now, somewhere else Kyle wrote that he actually wanted to achieve an
"old-style/western-like" B/W look. That would probably mean a more
brownish/yellowish, probably even scratched and "weathered" look, and *that*
is a totally different story ;-)
Johannes.
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On Fri, 12 Mar 1999 21:41:02 -0500, Kyle <joe### [at] geocitiescom>
wrote:
>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
By no means do I wish to sound inmodest, but if you would care to test
the solution I offered (I haven't tested it yet), I bet my disability
pension that it will work. If you want to make it look like a really
old picture, yellowish/brown in color, with scratches etc., it is all
a matter of texturing the height_field properly. You can even try to
make it kinda burnt along the edges in the following way:
1. Make the HF16G png
2. Render a b&w HF blah blah (as I explained)
3. Get the image from step 2, apply it to a height_field and overlay
another texture, probably a boxed pattern that is clear inside and
black around 0.95 and above, with some turbulence.
4. Now using the result from step 3 as a height_field with a
water_level of, say, 1/255, the edges will look eaten away. Apply the
gradient pattern you want (black->brown->yellowish ?) and overlay it
with the same boxed pigment from step 3, this time a little more
blurry , like
color_map
{
[0 color Clear]
[0.9 color Clear]
[0.9 color Brown filter 1]
[1 color Brown filter 0]
}
and apply the same turbulence as you did in step 3.
HTH
---------
Peter Popov
ICQ: 15002700
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