How to extract main branch coordinates from this corneal nerves image

Hi. I got a picture of a manual segmented corneal nerves.

I wanted to extract the coordinates of the nerves that branches, like these:

I've tried using some algorithm that search for the longest path of line in the image, but it just produce the results that I don't want, such as

Does anyone know how to do this? Thank you so much in advance.

Answer 1

[Maneet Kaur Bagga]

Hi Win,

As per my understanding instead of searching for the longest path of a line, consider using image processing techniques to detect and extract the branching points and the corresponding nerve segments.

Please refer to the following as a workaround:

• Apply image enhancement techniques such as smoothing to improve the quality of the image and make subsequent processing more effective.
• Use edge detection algorithm like Sobel operator to identify the edges of the nerves in the image. This will help in segmenting the nerves from the background.
• Apply a segmentation algorithm such as thresholding to separate the nerves from the background. This will create a binary image with the nerves as foreground pixels.
• Using "skeletonization" extract the skeleton or centerline of the segmented nerves. Then, identify the branching points by detecting the junctions or intersections in the skeleton.
• From each branching point, trace the nerve segments by following the skeleton or centreline. Use algorithms like depth-first search (DFS) or breadth-first search (BFS) to traverse the skeleton and extract the coordinates of the nerve segments.

Please refer to the following MATLAB Documentation for the implementation of the above algorithms:

Image Enhancement

https://www.mathworks.com/discovery/image-enhancement.html

Sobel function

https://www.mathworks.com/help/coder/ug/edge-detection-on-images.html

Image Thresholding

https://www.mathworks.com/discovery/image-thresholding.html

Regards,

Maneet Bagga