"bwtraceboundary" help in matlab

Hi, I am having trouble using the built-in function. Previously, I was able to use bwboundary for other images to get boundaries. However somehow, for certain image I am currently analyzing, I am not able to get the boundary array. I get empty array. Below is the code

cropi = i(start_row:264, start_col:626, :);

boundary_left = bwtraceboundary(cropi, [85, 33], 'W', 8, 10, 'clockwise');

boundary_top = bwtraceboundary(cropi, [16, 3], 'S', 8, 10, 'counterclockwise');

[85, 33] and [16,3] are strating points and I specified the directions as above. Although the image is similar to others I analyzed previoulsy, I get empty array. I wasn't able to upload image but if needed I will send in email.

Thank you very much :)

Answer 1

[Image Analyst]

You have a 3D image. You're getting rows start_row to 264, and columns from start_col to 626, and all slices (or all color channels) from the (very badly-named) i. Exactly how do you intend it to trace a boundary in 3D?

[Taehyung]

This is not 3-D but 2-D gray scale image. It would be clear if I posted the image. Thank you very much for comment. I was able to figure out the error I was having.

Have a nice day.

[Walter Roberson]

http://www.mathworks.com/matlabcentral/answers/7924-where-can-i-upload-images-and-files-for-use-on-matlab-answers