How to find threhold values

Hi all,

Hope to get some help here.

I have a 2d array of size 1000x1000 that contains values. I would need to identify the shape of the lowest region (darkest blue) and do some processing. Do you guys have any idea on how I should proceed to identify the shape of it?

I thought of finding the lowest point in the whole grid and extend in all directions from there. But again, I do not know the threshold of the dark blue region compared to the lighter ones. So help in this would also be very much appreciated.

Thank you!

Answer 1

[Image Analyst]

You can get a binary "map" of where the image is lower than some amount, like

darkParts = grayImage < 0.005;

but then we need to know exactly what you want to know. What shape descriptors would be useful to you? The area? The perimeter? The circularity = Perimeter^2/(4*pi*area)?

Perhaps this would be useful for you: http://www.mathworks.com/matlabcentral/fileexchange/35452-finddepressions