given a contour returned by contourf,how to display the pixel values within a region

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.

[KSSV]

Do you have the coordinates of the region you want?

[Adam Danz]

Why not just click within the region and view the datatip showing the levels?

[Sparsh Garg]

Update: seems I have found a rough soln

first I use imcontour to get the contour of a level X,I save that image then run imtool on it to get a understanding of the pixel values for that contour.

Now the problem here is that if I wanted to look at the pixel values for contour level Y and X at the same time,I don't think I can do that .Or can I.

Contour at level 55

contour at another level 50

Pixel values for contour 55

Pixel value for contour 50

So is there a way in which I can show the two figures on one figure ,i tried doing hold on but it doesn't work.

Bottom line :I am able to get pixel value for contour using a combination of imcontour and imtool,but I would like to display all the contour pixel values together.

[Sparsh Garg]

thanks for the input,but this is what I was asked to do,and apparently the guy above me seems satisified with what I gave him.

Don't beat the messenger.

Answer 1

[DGM]

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

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);

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