Extract outermost contour from a set of contours.
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Meghana Dinesh
le 20 Déc 2014
Commenté : Image Analyst
le 22 Déc 2014
I have an N X 2 matrix with the x,y co-ordinate values of the edges. I plot these co-ordinates (plotted in red displayed below in "Input Plot")
![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/146539/image.bmp)
I want to extract the outermost contour (enclosing the largest area). How can this be done?
I have attached the N X 2 matrix with all x, y values (of input plot). I have also attached a .fig file of the input plot.
Regards.
2 commentaires
Geoff Hayes
le 20 Déc 2014
Sanya - you didn't attach the data and figure. Once you have chosen the file, you must press the Attach File button.
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Image Analyst
le 20 Déc 2014
I think using contour is the wrong approach, but I could be wrong. You don't even want all the contours -- you just want the outer boundary . What I would do is to threshold your image, then call imfill() to make the binary image solid, and then call bwareaopen() to get rid of the small noisy exterior regions. Then call bwboundaries to get a list of the outer perimeter's (x,y) coordinates.
binaryImage = grayImage > thresholdValue; % Threshold/binarize the image.
binaryImage = imfill(binaryImage, 'holes'); % Fill holes.
binaryImage = bwareaopen(binaryImage, 2000); % Remove small blobs.
boundaries = bwboundaries(binaryImage); % Get list of (x,y) coordinates of outer perimeter.
Attach your image if you want more help.
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Image Analyst
le 22 Déc 2014
No it doesn't. If you're going to deal with the image, like make measurements from it, you need to deal with pixels. Of course you can always upsize your image with imresize() to create more pixels.
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