Problem with colormap!
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Nguyen Tan Duoc
on 15 Aug 2015
Commented: Image Analyst
on 21 Aug 2015
I have a CT image (a matrix 512 x 512) that has maximum value is 2062 and minimum ones is 64. I want to show it so that the maximum pixel get white and the minimum ones get black color. I tried to use function colormap(C), with C=[a a a], a=[0:1/2000:1]'.Then used function image (CT)to show it. I imagined a color bar that begin with black (at 1) and change along with shade value to white (at 2062 or less than that a little). But i got a figure with weird color bar. It's discrete and just black and gray like the attached image (hadn't used function image(CT) yet). I'm wondering what's wrong!
Accepted Answer
Walter Roberson
on 15 Aug 2015
This of course has nothing to do with the CT image; the question could have been posed without mentioning it.
On OS-X it looks fine:
My speculation is that you are using MS Windows and using a release before R2014b. Before R2014b, MATLAB on MS Windows only supported 256 entries in the color map. I am told that from R2014b onwards that the limit is substantially higher.
5 Comments
Image Analyst
on 21 Aug 2015
You're welcome. Hopefully your final decision was to use imshow() and not image() with that colormap you tried to create.
More Answers (1)
Image Analyst
on 15 Aug 2015
Don't use image(). Use imshow():
imshow(CT, []); % Be sure to use [].
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