POV-Ray : Newsgroups : povray.object-collection : Set of scalable colormaps recommended for scientific visualisation Server Time
14 Apr 2024 07:38:32 EDT (-0400)
  Set of scalable colormaps recommended for scientific visualisation (Message 1 to 9 of 9)  
From: yesbird
Subject: Set of scalable colormaps recommended for scientific visualisation
Date: 19 Feb 2023 18:29:46
Message: <63f2b0ea@news.povray.org>
This is a set of ready-to-use colormaps, each contains 256 colors. Most 
of them exported from Matlab, other from this page: 
https://www.kennethmoreland.com/color-advice/

Color information stored in 2D array, colormaps are generating by the 
macro, allowing re-scaling and applying desired transparency.
Usage examples also present.

Download: https://github.com/syanenko/Colormaps
--
YB


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From: Cousin Ricky
Subject: Re: Set of scalable colormaps recommended for scientific visualisation
Date: 19 Feb 2023 20:50:25
Message: <63f2d1e1$1@news.povray.org>
On 2023-02-19 19:29 (-4), yesbird wrote:
> This is a set of ready-to-use colormaps, each contains 256 colors. Most
> of them exported from Matlab, other from this page:
> https://www.kennethmoreland.com/color-advice/
> 
> Color information stored in 2D array, colormaps are generating by the
> macro, allowing re-scaling and applying desired transparency.
> Usage examples also present.
> 
> Download: https://github.com/syanenko/Colormaps

I see no mention of gamma in Mr. Moreland's article, nor in any of the
papers he linked.  Online colors are typically sRGB or gamma 2.2 (with
good reason), but your tool is set to gamma 1.0 (also with good reason),
and there are no srgb keywords or exponentiation in your code.  In the
absence of documentation to the contrary, color definitions tend to
default to sRGB, often simply because the author is completely unaware
that color non-linearity is a thing.  How can we be sure that you have
interpreted Mr. Moreland's colors correctly?

I am unfamiliar with MatLab.  Does it address color gamma?


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From: yesbird
Subject: Re: Set of scalable colormaps recommended for scientificvisualisation
Date: 20 Feb 2023 05:06:44
Message: <710228e9-9917-2c5b-9e0d-c7c21533e12e@gmail.com>
> I see no mention of gamma in Mr. Moreland's article, nor in any of the
> papers he linked.

Hi Cousin,
Thanks for your comment and interesting question. I am not sure that 
gamma correction is so important for scientific visualization. This is 
not photography, where we trying to achieve highest realistic level, 
colors only helps to interpret model more accurate, they are 
'suppositive' here.

I any case, if someone need it, he can implement macro, processing data 
array according his requirements (thanks to Bald for advice to store 
data separately of their interpretation).

 > I am unfamiliar with MatLab.  Does it address color gamma?

As to Matlab, yes, it has methods for gamma correction, but not at 
colormap, but at image level:
https://www.mathworks.com/help/images/ref/lin2rgb.html
--
YB


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From: Tor Olav Kristensen
Subject: Re: Set of scalable colormaps recommended for scientific visualisation
Date: 1 Mar 2023 13:00:00
Message: <web.63ff91b82f3c3b63bebf0bf589db30a9@news.povray.org>
yesbird <sya### [at] gmailcom> wrote:
> This is a set of ready-to-use colormaps, each contains 256 colors. Most
> of them exported from Matlab, other from this page:
> https://www.kennethmoreland.com/color-advice/
>
> Color information stored in 2D array, colormaps are generating by the
> macro, allowing re-scaling and applying desired transparency.
> Usage examples also present.
>
> Download: https://github.com/syanenko/Colormaps

Hi YB

It's good that you have now included a license file in this repository and that
you mention where the color maps came from.

But are you sure that the "GNU Affero General Public License v3.0" compatible
with the licenses from the initial authors?

And are you aware that this license is more strict than the original licenses
that came with some of the color maps?

Also, I think that the original authors will appreciate it if you give them some
credit by mentioning their names somewhere in the code or on the repository
page.

--
Tor Olav
http://subcube.com
https://github.com/t-o-k


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From: yesbird
Subject: Re: Set of scalable colormaps recommended for scientific visualisation
Date: 1 Mar 2023 13:25:13
Message: <79c34d03-6315-1a2e-1294-f3503ff3be50@gmail.com>
On 01/03/2023 20:56, Tor Olav Kristensen wrote:
> But are you sure that the "GNU Affero General Public License v3.0" compatible
> with the licenses from the initial authors?
> 
> And are you aware that this license is more strict than the original licenses
> that came with some of the color maps?
Hi, Tor.
Thank you for pointing me to this potential problem, I thought about it,
but unfortunately too far from licensing details. If you have more info
about that, maybe you can suggest to me the license that will 'best-fit'
to this publication ? If not, I will need to explore this area more
seriously.

> Also, I think that the original authors will appreciate it if you give them some
> credit by mentioning their names somewhere in the code or on the repository
> page.
This is a good idea, will do it for sure.

All the best,
--
YB


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From: Tor Olav Kristensen
Subject: Re: Set of scalable colormaps recommended for scientific visualisation
Date: 1 Mar 2023 19:35:00
Message: <web.63ffebac2f3c3b63383c879289db30a9@news.povray.org>
yesbird <sya### [at] gmailcom> wrote:
> On 01/03/2023 20:56, Tor Olav Kristensen wrote:
> > But are you sure that the "GNU Affero General Public License v3.0" compatible
> > with the licenses from the initial authors?
> >
> > And are you aware that this license is more strict than the original licenses
> > that came with some of the color maps?
> Hi, Tor.
> Thank you for pointing me to this potential problem, I thought about it,
> but unfortunately too far from licensing details. If you have more info
> about that, maybe you can suggest to me the license that will 'best-fit'
> to this publication ? If not, I will need to explore this area more
> seriously.

Note that I'm not claiming that there is a problem - and I do not know
much about copyright law.

I was just a bit surprised when I saw that license, since the license
for Inferno, Plasma and Viridis seems to be CC0 (i.e. no copyright).

https://github.com/BIDS/colormap
http://creativecommons.org/publicdomain/zero/1.0

Inferno and Plasma was made by Stefan van der Walt and Nathaniel Smith,
while Viridis was made by Eric Firing and then modified by Stefan van
der Walt and Nathaniel Smith.

I recommend that you try to find the original author of each of the
other color maps and then try to find out if they specified any
licenses for their code. - Yes; that is probably a lot of work with
that many color maps.

Here's a Wikipedia page that might be useful for you, especially the
section about compatibility, if you are going to use licenses that are
different that the ones the original authors specified:

https://en.wikipedia.org/wiki/Open-source_license

--
Tor Olav
http://subcube.com
https://github.com/t-o-k


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From: yesbird
Subject: Re: Set of scalable colormaps recommended for scientific visualisation
Date: 1 Mar 2023 19:51:52
Message: <817f547d-528c-64bf-c632-a28b5d034045@gmail.com>
On 02/03/2023 03:29, Tor Olav Kristensen wrote:
> Inferno and Plasma was made by Stefan van der Walt and Nathaniel Smith,
> while Viridis was made by Eric Firing and then modified by Stefan van
> der Walt and Nathaniel Smith.
Thanks a lot for this info, I had to find it myself, not you :)

> I recommend that you try to find the original author of each of the
> other color maps and then try to find out if they specified any
> licenses for their code. - Yes; that is probably a lot of work with
> that many color maps.
Agree with you, this work should be done, it's better to do everything
correctly.

> Here's a Wikipedia page that might be useful for you, especially the
> section about compatibility, if you are going to use licenses that are
> different that the ones the original authors specified:
> 
> https://en.wikipedia.org/wiki/Open-source_license
Thanks again, I will read it, in any case it's better to know all
licensing rules for the future.
--
YB


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From: Cousin Ricky
Subject: Re: Set of scalable colormaps recommended for scientific visualisation
Date: 2 Mar 2023 16:16:18
Message: <64011222@news.povray.org>
On 2023-03-01 20:29, Tor Olav Kristensen wrote:
> 
> I was just a bit surprised when I saw that license, since the license
> for Inferno, Plasma and Viridis seems to be CC0 (i.e. no copyright).

It may not make much practical difference, but this is better phrased as
"copyright waived."  In some jurisdictions it is not legally possible to
give up your copyright, thus the need for dedication licenses such as CC0.


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From: Tor Olav Kristensen
Subject: Re: Set of scalable colormaps recommended for scientific visualisation
Date: 3 Mar 2023 09:40:00
Message: <web.6402062f2f3c3b63d105cea189db30a9@news.povray.org>
Cousin Ricky <ric### [at] yahoocom> wrote:
> On 2023-03-01 20:29, Tor Olav Kristensen wrote:
> >
> > I was just a bit surprised when I saw that license, since the license
> > for Inferno, Plasma and Viridis seems to be CC0 (i.e. no copyright).
>
> It may not make much practical difference, but this is better phrased as
> "copyright waived."  In some jurisdictions it is not legally possible to
> give up your copyright, thus the need for dedication licenses such as CC0.

I think that this is a rather strange license.

IIRC Norway is such a jurisdiction where it's not possible to
renounce one's copyright.

On the Wikipedia page I linked to there's a "Open-source software
licenses and how they interact" diagram. If I interpret this
diagram correctly, then it seems that it is actually ok to use
LGPL for works derived from something in the public domain.

--
Tor Olav
http://subcube.com
https://github.com/t-o-k


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