| Re: Color table questions [message #38138] |
Sat, 21 February 2004 15:01  |
R.Bauer
Messages: 1424
Registered: November 1998
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Senior Member |
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Michael Wallace wrote:
> Haje Korth wrote:
>> Mike,
>> You should toss that rainbow colorbar if you do science. This color bar
>> is highly non-linear to the human eye and you tend to emphasize features
>> that a completely non-physical, but rather due to changes in the gradient
>> of the color bar it self. I did actually some research on that a while
>> ago. I found one article that illustrates the topic well:
>>
>> B. E. Rogowitz and L. A. Treinish, How to NOT lie with visualisation,
>> Computers in Physics, vol10, no 3, 1996. (Make sure you get a color copy,
>> otherwise you will not be able to verify what the authors are talking
>> about.)
>>
>> The topic says it all: Pretty pictures alone do not guarantee good
>> science! I am not trying to be arogant (not my nature), this is just a
>> simple statement that I had to find out the hard way myself.
>
> Yes! That's exactly why I want to toss out the rainbow color bar --
> because it is very non-linear to the human eye. So, simply put, I'd
> like a colorbar that is linear (or as close as reasonable) to the human
> eye but still includes several distinct colors. I only mentioned the
> rainbow color bar because it includes several colors which flow together
> nicely. What it doesn't have is linear spacing between colors.
>
> I'm asking the question because, other than simple gradients, I haven't
> completely figured out how to make not only a good looking colorbar, but
> one that's also linear. I would have thought that someone else out
> there might also want to do this...
>
> As for the article you mention, that should be on the reading list of
> anyone who does science data analysis with colors. Here's an on-line
> version:
> http://www.research.ibm.com/dx/proceedings/pravda/truevis.ht m
>
> Mike
Dear Mike,
we have some nice colortables in our library,
for example: ct_blue_green_yellow_red
You find them in the library catalogue.
http://www.fz-juelich.de/icg/icg-i/idl_icglib/idl_source/idl _html
idl_work_libraries.htm
Please have look at the following site too:
http://www.fz-juelich.de/icg/icg-i/idl_icglib/idl_lib_intro. html
regards
Reimar
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