> Thus -- assuming I got the colour physics right on this one -- for
> proper representation of the actual Munsell pigments you'd need to
> divide the pigment colours by the colour of illuminant C, in order to
> undo the presumed white point bias. (Theoretically you'd need to to this
> in continuous spectrum space; in practice, you should do this in either
> XYZ or sRGB space, but whatever you choose it will be imprecise.)

That sounds about right.

What is also worth mentioning is that the human vision system is very 
good at figuring out what that underlying "unbiased" colour is by doing 
the division for you automatically. It figures out the illuminant colour 
from the surrounding view, so can be tricked/misled. What this means is 
that you could have exactly the same RGB value on two different coloured 
backgrounds, and you will be convinced the RGB value is different.

Post a reply to this message

> Okay, I just re-rendered the scene specifying #version 3.6 instead of
> #version 3.7. There is a huge difference! I cannot explain it however. I
> don't know why there is such a big difference.

What might me worth doing is to add 4 "control" blocks, where you set 
the xyY values to that of the sRGB primaries and the white point:

https://en.wikipedia.org/wiki/SRGB

In theory those should end up as pure red,green,blue and white on your 
final image, and would highlight any lighting issues with the scene.

Post a reply to this message

On 11/23/2015 9:50 PM, Cousin Ricky wrote:
> That would help, wouldn't it?  But I haven't seen any Munsell data set
> with any gray values.
>

On Wikipedia there are gray values, as well as pure white and pure black.


Mike

Post a reply to this message

Am 24.11.2015 um 04:23 schrieb Cousin Ricky:
> On 11/23/2015 09:31 PM, Mike Horvath wrote:
>> I just noticed that there are sRGB values in a spreadsheet here:
>>
>> http://www.rit.edu/cos/colorscience/rc_munsell_renotation.php
> 
> The 1943 renotation is an extrapolation of the 1929 data set, and is
> thus far more comprehensive.  It would certainly be more useful than
> what you have now.  However...
> 
>> I may just use those instead. But are they copyrighted?
> 
> With a vengeance:  http://www.rit.edu/terms_of_use.html

More concise:

http://www.rit.edu/disclaimer.html

In a nutshell:

Personal use only, i.e. no redistribution whatsoever.
Noncommercial use only, i.e. no making money out of it whatsoever.

Post a reply to this message

Am 24.11.2015 um 04:23 schrieb Cousin Ricky:

> Note "derivative works" in their language.  Also note the Copyright
> Infringement link, which wields the DMCA.  These people sound serious. I
> have rendered the 1943 data myself, but I dare not publish it. At least
> the copyright on the 1929 data has expired.  If it makes you feel
> better, most of the extra 1943 points are outside the sRGB gamut anyway.

Erm... careful about the 1929 data:

"These are only those colors physically appearing in the 1929 Munsell
Book of Color. These data might be of useful for those interested in the
input colors used for the scaling experiments leading to the 1943
renotation. Remember though, these are renotation colors of those
original patches, not necessarily the colors of the input data used in
the visual experiment."

In other words, the "1929" data wasn't measured and published in 1929;
instead, it is a true subset of the 1943 data, and as such is subject to
the same copyright restrictions.

There /do/ seem to have been colorimetric measurements of the Munsell
atlas in 1929, but that's not what's in the "1929.dat" available from
RIT or other sources.

Post a reply to this message

Am 11/22/2015 um 20:55 schrieb Mike Horvath:
> I am trying to re-render the Munsell color cylinder scene from the
> object collection. However, the results look too drab. Compare it to this:
>
> https://commons.wikimedia.org/wiki/File:Munsell_1929_color_solid.png
>
> Does anyone have any tips to improve the render?
>
>


As Cousin Ricky did dig up that this xyY data uses illuminant C you need 
to "tell" this CIE.inc otherwise you won't get the hues right.
There is the macro CIE_ReferenceWhite() for exactly this purpose. The 
CIE.inc default is D50 (not D65!) as all reflectance data that 
accompanies lightsys uses D50 (and all spectrophotometer I am aware of).
Anyway, a call to CIE_ReferenceWhite with the appropriate illuminant 
will result in a recalculation of the chromatic adaption matrices and 
the xyz->rgb transformation matrices.

For the washed out look of your render itself, if you want to reproduce 
the image of the wikipedia page: there is the 3d shading look just faked 
(by making the block sides slightly darker than the tops) so no GI and 
not even a light source is used. This makes sense because the focus of 
this image is the hue of the Munsell colors.

-Ive (who once wrote CIE.inc but is meanwhile retired and ATM quite 
addicted to Dota2)

Post a reply to this message

Am 24.11.2015 um 02:31 schrieb Mike Horvath:

> I may just use those instead. But are they copyrighted?


(Disclaimer: IANAL. No guarantee for the correctness of the following
statements.)


If you want data free of copyright issues, look at the following papers:

http://nvlpubs.nist.gov/nistpubs/jres/31/jresv31n2p55_A1b.pdf
http://www.rit-mcsl.org/MunsellRenotation/MunsellRe-renotations.pdf

Both papers, published in the U.S. in 1943 and 1969 respectively, don't
carry any copyright notice, so according to
https://copyright.cornell.edu/resources/publicdomain.cfm they should be
in the public domain (first published in the U.S., in the years
1923-1977, without a copyright notice).

Note that the 1943 paper probably describes the original, non-renotated
Munsell colours, while the 1969 paper describes a different re-notation,
so neither matches the commonly used renotated Munsell colours.


Having said that, it also seems worth taking a closer look at the 1943
renotation article's copyright status:

Titled "Final Report of the O.S.A. Subcommittee on the Spacing of the
Munsell Colors", and published in the "Journal of the Optical Society of
America" in 1943, the OSA Publishing claims it to be (C) 1943 Optical
Society of America, so I presume there's a copyright notice in the paper
itself.

However, copyrights to works first published in the U.S. in the years
1923 to 1963 have all expired after 28 years, *if* they haven't been
explicitly renewed in their 28th year; renewal is only possible through
registration with the U.S. Copyright Office. Thus, for the 1943's
paper's copyright to still be valid, it would have to have been
registered for renewal somewhere between 1970 and 1971, and should thus
appear in the Copyright Office's official archives for those years, or
1972 the latest.

Now guess what: Having had a quick look at scans of the 1970-1972
archives, it seems that neither the "Journal of the Optical Society of
America" in general, nor the article "Final Report of the O.S.A.
Subcommittee on the Spacing of the Munsell Colors", have been registered
for copyright renewal in those years.

Thus, if my observations are correct, then the 1943 renotation paper is
in the public domain by now, too.


This would also have implications for the data files: Insofar as they
are compilations of xyY colour coordinates from the 1943 renotation
paper, their contents should be free for re-distribution in different
formats (such as a POV-Ray include file), as -- quoting from the U.S.
Copyright Office's publucation at http://copyright.gov/circs/circ14.pdf:

"The copyright in a compilation of data extends only to the
selection, coordination or arrangement of the materials or
data, but not to the data itself."

Note however that it would be prudent to verify that the data in the
files is in fact identical to the data in the paper, and doesn't contain
any additional data points. Unfortunately, as mentioned already, the
1943 renotation paper is closely guarded and doesn't appear to be
available for free anywhere, so that would mean you'd have to buy the
paper first.

Post a reply to this message

On 11/24/2015 5:30 AM, Ive wrote:
> Am 11/22/2015 um 20:55 schrieb Mike Horvath:
>> I am trying to re-render the Munsell color cylinder scene from the
>> object collection. However, the results look too drab. Compare it to
>> this:
>>
>> https://commons.wikimedia.org/wiki/File:Munsell_1929_color_solid.png
>>
>> Does anyone have any tips to improve the render?
>>
>>
>
>
> As Cousin Ricky did dig up that this xyY data uses illuminant C you need
> to "tell" this CIE.inc otherwise you won't get the hues right.
> There is the macro CIE_ReferenceWhite() for exactly this purpose. The
> CIE.inc default is D50 (not D65!) as all reflectance data that
> accompanies lightsys uses D50 (and all spectrophotometer I am aware of).
> Anyway, a call to CIE_ReferenceWhite with the appropriate illuminant
> will result in a recalculation of the chromatic adaption matrices and
> the xyz->rgb transformation matrices.
>

Okay thanks!

> For the washed out look of your render itself, if you want to reproduce
> the image of the wikipedia page: there is the 3d shading look just faked
> (by making the block sides slightly darker than the tops) so no GI and
> not even a light source is used. This makes sense because the focus of
> this image is the hue of the Munsell colors.
>

The problem is that POV 3.6 and 3.7 produce totally different results, 
even when using #version 3.6.

> -Ive (who once wrote CIE.inc but is meanwhile retired and ATM quite
> addicted to Dota2)
>
>
>
>

Post a reply to this message

On 11/24/2015 6:58 AM, clipka wrote:
> Am 24.11.2015 um 02:31 schrieb Mike Horvath:
>
>> I may just use those instead. But are they copyrighted?
>
>
> (Disclaimer: IANAL. No guarantee for the correctness of the following
> statements.)
>
>
> If you want data free of copyright issues, look at the following papers:
>
> http://nvlpubs.nist.gov/nistpubs/jres/31/jresv31n2p55_A1b.pdf
> http://www.rit-mcsl.org/MunsellRenotation/MunsellRe-renotations.pdf
>
> Both papers, published in the U.S. in 1943 and 1969 respectively, don't
> carry any copyright notice, so according to
> https://copyright.cornell.edu/resources/publicdomain.cfm they should be
> in the public domain (first published in the U.S., in the years
> 1923-1977, without a copyright notice).
>
> Note that the 1943 paper probably describes the original, non-renotated
> Munsell colours, while the 1969 paper describes a different re-notation,
> so neither matches the commonly used renotated Munsell colours.
>
>
> Having said that, it also seems worth taking a closer look at the 1943
> renotation article's copyright status:
>
> Titled "Final Report of the O.S.A. Subcommittee on the Spacing of the
> Munsell Colors", and published in the "Journal of the Optical Society of
> America" in 1943, the OSA Publishing claims it to be (C) 1943 Optical
> Society of America, so I presume there's a copyright notice in the paper
> itself.
>
> However, copyrights to works first published in the U.S. in the years
> 1923 to 1963 have all expired after 28 years, *if* they haven't been
> explicitly renewed in their 28th year; renewal is only possible through
> registration with the U.S. Copyright Office. Thus, for the 1943's
> paper's copyright to still be valid, it would have to have been
> registered for renewal somewhere between 1970 and 1971, and should thus
> appear in the Copyright Office's official archives for those years, or
> 1972 the latest.
>
> Now guess what: Having had a quick look at scans of the 1970-1972
> archives, it seems that neither the "Journal of the Optical Society of
> America" in general, nor the article "Final Report of the O.S.A.
> Subcommittee on the Spacing of the Munsell Colors", have been registered
> for copyright renewal in those years.
>
> Thus, if my observations are correct, then the 1943 renotation paper is
> in the public domain by now, too.
>
>
> This would also have implications for the data files: Insofar as they
> are compilations of xyY colour coordinates from the 1943 renotation
> paper, their contents should be free for re-distribution in different
> formats (such as a POV-Ray include file), as -- quoting from the U.S.
> Copyright Office's publucation at http://copyright.gov/circs/circ14.pdf:
>
> "The copyright in a compilation of data extends only to the
> selection, coordination or arrangement of the materials or
> data, but not to the data itself."
>
> Note however that it would be prudent to verify that the data in the
> files is in fact identical to the data in the paper, and doesn't contain
> any additional data points. Unfortunately, as mentioned already, the
> 1943 renotation paper is closely guarded and doesn't appear to be
> available for free anywhere, so that would mean you'd have to buy the
> paper first.
>

I think the simpler answer is to discontinue this project and remove my 
image from Wikipedia and the Object Collection.


Mike

Post a reply to this message

Am 24.11.2015 um 18:25 schrieb Mike Horvath:

> The problem is that POV 3.6 and 3.7 produce totally different results,
> even when using #version 3.6.

Didn't someone just say that the results are identical?

There's one more thing that might make a difference: The Display_Gamma
ini file setting in 3.6, v.s. the Display_Gamma and File_Gamma ini file
settings in 3.7.

Post a reply to this message