The NaN values outside of my shape should be one color (gray/white) but without changing the value of my polygon inside my shape (value 10-100). When I use imagesc(~isnan(CP)) the value of my polygons are overwritten with value of 1.
Distinct NaN from other values in image
20 views (last 30 days)
Show older comments
I want to plot image with different values and easily distinct them from NaN values. As default NaN values are imaged with the same color as the minimum value. I have tried a range of possibilites but each provide their own issue. Here is one example:
imagesc(CP)
sc(isnan(CP), 'bone', [1 1 1]);
3 Comments
Image Analyst
on 25 Nov 2013
The answer has been accepted. I don't see a question in the last comment. And no m-file was attached.
Accepted Answer
Iain
on 21 Nov 2013
This can let you plot NaN & any other logically findable section of the image as white
a = rand(5);
a(3,3) = NaN;
b = imagesc(a);
set(b,'AlphaData',~isnan(a))
Alternatively, you can deliberately control the "colormap" settings to ensure that "invalid" values show up as a colour that isn't used by the colour map.
3 Comments
More Answers (1)
Image Analyst
on 20 Nov 2013
I don't know what "plot" means when talking about an image. I don't know why you want to plot anything on an image, like markers to "cover up" the nan locations. Why not just set the nan's to the min gray level and view it like a normal image?
CP(isnan(CP)) = min(CP(:)); % Set nan values to the min value
image(CP);
colormap(bone(256));
colorbar;
3 Comments
Image Analyst
on 22 Nov 2013
Sorry but I don't understand this. One just sort of looks like a very blurred version of the other. Both have the same pattern of triangles on them, and I don't even know what a triangle means/represents. Your image is an array. You can't have nan values have the same value as your minimum value. An element can have only one value, either a nan or some number. It can't have both at the same time. So "Nan values are imaged with the same color as my minimum value" makes no sense to me.
See Also
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!