How can I grab the contour lines into a new figure ?

Uni
2013 6 7
2 个回答
回答已采纳
3 次查看（30 天）

0 个投票

I am using contour function to get the contour lines from an image. Now I'd pretend to get only the contour lines created before to make a new image.
I am using [C,h]=contour(a,[0 0]); I have C - ContourMatrix and h - handler.
How can I create a new image (only contour lines) with this C and h ??
Thanks in Advance Mike

请先登录，再回答此问题。

 采纳的回答

Kelly Kearney
Kelly Kearney 2013-6-7

0 个投票

Easiest way: download contourcs, which will parse the C matrix for you.
a = peaks;
C = contourcs(a, [0 0]);
xy = {C.X; C.Y};
plot(xy{:});

9 个评论
显示 7更早的评论 隐藏 7更早的评论

Uni
Uni 2013-6-8
yeah, that's what I need :)
but I have much different contour lines from contourcs compared to contour function. :/
any clue ?
Uni
Uni 2013-6-8
Oops my bad, its the same contour with a few transformations, rotations and shape.
Is there a way to get the contour lines fixed on a same image size ?
Kelly Kearney
Kelly Kearney 2013-6-10
You shouldn't need any transformations... assuming you pass identical input to both contour and contourcs, the output contours should be identical. Perhaps if you give some example data and describe how you're trying to display the results, we can figure out what's going on.
Uni
Uni 2013-6-10
these are the two images contours: http://oi39.tinypic.com/2wnbbsm.jpg
left side is using contour function;
right side is using contourcs function;
-------------------------------
function [C,C1]=showCurveAndPhi(I, phi, i)
imshow(I,'initialmagnification',200,'displayrange',[0 255]); hold on;
[C] = contourcs(phi, [0 0]);
[C1]=contour(phi, [0 0], 'g','LineWidth',2);
hold off; title([num2str(i) ' Iterations']); drawnow;
-----------------
The first image is plotted in "real time" using the above function to make the contour and I am plotting C from contourcs() like you told me before:
-----------------
xy = {C.X; C.Y};
figure; plot(xy{:});
------------------
why the contour lines are so different ?
Thanks in advance
Mike
Uni
Uni 2013-6-10
编辑：Uni 2013-6-10
http://oi39.tinypic.com/2wnbbsm.jpg this image seems like just need to flip the contours lines.
but if by some reason the contour lines was like this image http://oi44.tinypic.com/fktmqd.jpg I have the contour but with different image size.
Thanks again ;)
Kelly Kearney
Kelly Kearney 2013-6-10
The values of the two plots are the same; they're just being displayed slightly differently. The imshow function is designed for images, so automatically sets the aspect ratio of the axis to 1:1; plot doesn't do this. Setting the 'xlim', 'ylim', and 'dataaspectratio' properties of the two axes to match each other should get the results you want, I think. Here's an example:
I = imread('coins.png');
level = graythresh(I);
BW = im2bw(I,level);
C = contourcs(double(BW), [0 0]);
xy = {C.X; C.Y};
ax(1) = subplot(2,1,1);
imshow(BW);
ax(2) = subplot(2,1,2);
plot(xy{:}, 'b');
props = get(ax(1), {'xlim', 'ylim', 'dataaspectratio'});
set(ax(2), {'xlim', 'ylim', 'dataaspectratio'}, props);
Uni
Uni 2013-6-11
http://oi44.tinypic.com/5d3wc5.jpg and about the turn of the contour lines? because the contour lines is upsidedown, compared to original coins and BW.
thanks a lot (:
Kelly Kearney
Kelly Kearney 2013-6-11
Oops, forgot that one... imshow also flips the axis. Add 'ydir' to the list of properties to copy.

请先登录，再进行评论。

更多回答（1 个）

Angus
Angus 2013-6-7

0 个投票

Try checking out ContourMatrix.
"ContourMatrix is also a read-only contourgroup property that you can obtain from the returned handle." -- matlab docs

1 个评论
显示 -1更早的评论 隐藏 -1更早的评论

Uni
Uni 2013-6-8
you mean I should rearrange my C variable from contour function to get the new image ?
thanks

请先登录，再进行评论。

类别

在 帮助中心 和 File Exchange 中查找有关 Contour Plots 的更多信息

标签

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by