Tutorial on structure tensors. Normally associated with image processing and structure inference, this code provides a completely encapsulated package to explain and demonstrate the use of structure tensors.
or use the html to properly visualize the LaTeX equations.
In function partial_derivative_to_structure_tensor_form,
it seems that it always output a diag matrix. Is it correct?
I am beginner in Matlab, and I need to extract structure tensor eigenvalues and eigenvectors combining three different scales (0.65, 1.1, and 2.5) for MRI images (dicom file format).Can we use these codes for this purpose? Your help is appreciated.
You give excellent examples of finding the structure tensor of a 3 dimensional image. I was wondering if you could post an example that finds the structure tensor of a 2d image.
I'd like to ask you about line 28 in structure_tensor_plot.m :
[stheta, sphi, srho] = cart2sph(e3(1), e3(2), e3(3));
Why did you use e3 instead of e1? since l1 >> l2 = l3 (aprox.) , it should be e1 that corresponds (l1). I would appreciate a lot if you answer my inquiry.
Thanks in advance.
I believe that your issue may be that you are using an older version of MatLab as I see from your directory path that you are using MatLab 6. To provide a quick fix, I suggest looking at your local help file (which should still have your appropriate function parameters) for 'quiver'. Otherwise, I suggest re-coding the source to:
quiver(midpt, midpt, cU, cV);
This won't have any of the cool visualization, but I suspect it may work for your version of MatLab. You can also try to re-code based on the premise that the current version of quiver works as follows:
quiver(xpos, ypos, xMagnitude, yMagnitude, scaleFactor, lineSpec, ...);
Hope that this helps you out.
??? Error using ==> quiver
Too many input arguments.
Error in ==> C:\MATLAB6p5\work\ST_pub\structureTensorDemo.m
On line 81 ==> quiver(midpt, midpt, cU, cV, midpt, 'r', 'LineWidth', 5, 'MaxHeadSize', 5);
Isotropic Case: Directional Derivative Magnitude=0.000000
Uniform Color Case: Directional Derivative Magnitude=0.000000
Note how the coherence measure is different for each case
Isotropic case coherence:0.000000
Uniform color case coherence:1.000000
??? Undefined command/function 'voxel_plot'.
Error in ==> visualize_3D_data at 30
Error in ==> structureTensorDemo at 341