How to crop image using imfreehand and save the output without connecting the boundaries

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Praveen GB 2019-12-19

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评论： Image Analyst 2019-12-20

I have an input Image, I want to crop the image using imfreehand with closed boundary option. Unfortunately when I create mask and save the output:

h = imfreehand('Closed',false);
output_mask = h.createMask();

the end points of the cropped region becomes a closed polygon.

This is input file

This is the required output.

I am getting this output

Thanks in advance

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回答（2 个）

Matt J 2019-12-19

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编辑：Matt J 2019-12-19

I think you simply neglected to trace the full boundary of the shape. Though I traced very quickly and unneatly, the result I get below shows what you should be getting when you trace the full boundary.

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Praveen GB 2019-12-20

编辑：Image Analyst 2019-12-20

Hi Matt, Thanks for the reply. I have so many such structures in a image, I want to manually crop these structures and find the edges as shown in the depicted output.

Thanks

Image Analyst 2019-12-20

Your depicted desired output does not show the edges - it shows the entire, filled blob.

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Image Analyst 2019-12-19

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在 MATLAB Online 中打开

If you want that output, why not simply binarize the image:

grayImage = imread('image.png');
if ndims(grayImage) == 3
	grayImage = rgb2gray(grayImage); % Convert RGB image into gray scale.
end
subplot(1, 2, 1);
imshow(grayImage);
binaryImage = ~imbinarize(grayImage);
subplot(1, 2, 2);
imshow(binaryImage);

It looks like the above image is what you said you want, so why do freehand masking?

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Praveen GB 2019-12-20

This is my input

and I want to crop the input and get output like

Since so many structures are present in input image, I have to crop it using free hand.

Thanks

Image Analyst 2019-12-20

OK, no explanation for why you need edges - I guess it's proprietary or something.

However my masking demo will allow you to mask freehand-drawn regions with optional cropping into a subimage if you want. Does it not do what you want? You can still detect edges if you feel that is definitely the best approach.

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