Increase one of the dimensions of an array

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Sebastian Dahl Sandbu 2023-6-17

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评论： Sebastian Dahl Sandbu 2023-6-17

I have a 190x190x20 array with intensity values of medical images (nifti). The resolution is (1mm, 1mm, 2mm), and I would like to have the same resolution in all directions. In other words, I want 40 pages instead of 20 pages.

Is there any way to increase the number of pages or increase the resolution in one direction? I have looked at interpolation, but I'm not sure if it will work in my case.

Greatful for any ideas.

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Stephen23 2023-6-17

编辑：Stephen23 2023-6-17

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"In other words, I want 40 pages instead of 20 pages."

You are making an off-by-one error. Consider:

V = 1:4
V = 1×4
     1     2     3     4
W = 1:0.5:4
W = 1×7
    1.0000    1.5000    2.0000    2.5000    3.0000    3.5000    4.0000

W has twice the resolution of V, but does it have twice the number of elements in it?

" I have looked at interpolation, but I'm not sure if it will work in my case."

Probably: what you describe is some kind of interpolation (using what method is another question entirely).

What have you tried so far?

Sebastian Dahl Sandbu 2023-6-17

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I see, thanks for the explanation.

So for mye array A, I have tried interp3(A), but that will increase the resolution in all dimension. I did also try the following, but without success.

[X, Y, Z] = size(A);
[Xq,Yq,Zq] = meshgrid(1:1:190,1:1:190,1:.5:39.5);
B = interp3(X, Y, Z, A, Xq, Yq, Zq);

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Answer 1

Image Analyst 2023-6-17

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Try interp3

help interp3

Something like (untested)

[rows, columns, slices] = size(img)
z = linspace(1, slices, 2 * slices); % Need twice as many slices as the original.
[X, Y, Z] = meshgrid(1:columns, 1:rows, z);
img2 = interp3(img, X, Y, Z);