given a contour returned by contourf,how to display the pixel values within a region
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So,lets say I run contourf on an image ,and I get the contour for a particular level
say I is the image and level is [55,55].
Then running contourf(I,level) gives me the contour for level 55.
Now I would like to observe the pixel values within a certain region just as imtool does,is there a way for doing this?
Any help will be appreciated.
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DGM
le 29 Juil 2021
Why are you trying to get the pixel value of a contour map? The pixel values of the contour map don't tell you anything about the image -- the shape of the contour does. What's worse is you're looking at the pixel values in a map that looks like it's been damaged by saving it as a JPG. This is meaningless information.
This is one attempt:
testpict = im2uint8(mat2gray(peaks(500))); % make a test image
imshow(im2double(testpict)); hold on % draw image
contour(testpict,[55,55]); % draw contour map over image
![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/697962/image.png)
The reason that the image is cast as double in the imshow() call is so that the pixel values are comparable to those used by contour(); otherwise, the contour lines won't be visible. Can the image be displayed in uint8 format with the contour overlay so that the datatip values are in uint8 range? I don't know. Maybe.
You can also just avoid the ambiguity of using a single-level contour map and just select a specific region and mask it off explicitly.
m = testpict <= 55;
maskedpict = im2uint8(im2double(testpict).*m);
imshow(maskedpict);
![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/697967/image.png)
Either way, you can get the values of the image pixels using impixelinfo() or a datatip, as has been suggested already.
impixelinfo % mouse over for current pixel coordinates and value
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