MATLAB Answers

Custom colormap being cut off in colorbar

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Pia on 8 Jan 2014
Commented: Image Analyst on 8 Jan 2014
I am trying to plot something with a manually added colormap, using something like the code below (this is just a minimal example showing my problem): I create some kind of matrix that has values between two known values, plot it with pcolor, and insert a colorbar.
Tmin=10; Tmax=320;
colmap = load('colorbartest_colormap.txt');
imagematrix = transpose(sqrt(linspace(Tmin,Tmax,10)))*sqrt(linspace(Tmin,Tmax,10));
This plots nicely with the standard colormap (jet), as shown in the screenshot:
however, if I try to use my own colormap with
I end up with the following:
and actually, even though I just use
I still get the problem, as:
Can anyone help me with what happens here? :(
I am using MATLAB vs. R2011a on Windows 7 64bit, if that has any importance.


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Accepted Answer

Image Analyst
Image Analyst on 8 Jan 2014
You can't have more than 256 color indexes - that's why it stops there.
Also, don't use pcolor() because it doesn't show you all the rows and columns of your image. That's why you see only a 9 by 9 array/grid instead of a 10 by 10 one.


Pia on 8 Jan 2014
Ah, then it makes sense - thank you so much for that! :)
Image Analyst
Image Analyst on 8 Jan 2014
Use image() or imshow() instead of pcolor(). You can have values outside the 0-255 range though. Run my attached demos.

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