Connecting missing boundary segments of particles in image

I have to segment each particle seapartely given in the image. I am trying to find its boundary edges. I have attached original image and obtained boundary image, I have to connect the missing boundary segments in the given image. Please help.

Answer 1

[Image Analyst]

Fixing the image capture problem can make the image processing so much easier. Why don't you just simply separate the rocks before you image them? Then just threshold, fill, and call bwboundaries.

mask = grayImage < someValue;
mask = imfill(mask, 'holes');
boundaries = bwboundaries(mask);

If you want to do it the hard way, which I strongly advise against, see Steve's blog:

http://blogs.mathworks.com/steve/2013/11/19/watershed-transform-question-from-tech-support/

[Vikrant Pratap]

I can't separate the rocks before imaging. The requirements is to segment the rocks in this way. The rocks are close to each other and overlapping with each other.

I have tried the below Steve's code but it's not working with my image. I have attached my binary image with the output result from steve's code. Some of the blobs are not separated with nearby blobs.

http://blogs.mathworks.com/steve/2013/11/19/watershed-transform-question-from-tech-support/

[Image Analyst]

If you don't like that result, then you'll either have to write a much more sophisticated algorithm, or manually separate them with imfreehand(). See attached demos.

By the way, WHY can't you separate them while you're taking the photo? It would make your life so much easier.

[Vikrant Pratap]

I can't use imfreehand() function as the model should not require human intervention.

I can't separate the particles before taking the image as it is real problem where rocks counting & size estimation has to be done. The rocks are close to each other and overlapping. Hence, I have to solve it in this way only.

It will be really helpful if you can help me in finding concave point in binary image. Then I cannect the missing boundary segments.

[Image Analyst]

Who is dictating all of these disabling requirements upon you? Do they want to get the job done or not? Who cares how it gets done as long as it gets done?