如何将 3D 导数矩阵重塑为 3x3xn 矩阵？

Question

我有 513x512x200 图像 Dxx、Dyx、Dyy、Dxz、Dzz、Dzy 的 3D 导数 其中 512x512 是 200 张图像的图像尺寸。 现在我想使用可以采用 3x3xn 矩阵的eig3 如何将这些矩阵重塑为 3x3xn 矩阵？

编辑

n 应该是体素的数量，3x3 矩阵应该是这样的

Dxx Dxy Dxz

Dyx Dyy Dyz

Daz Dzy Dzz

Answer 1

矩阵的操作可以通过使用'permute'和'reshape'来实现，如下所示。

 % say you saved your 2nd derivative 3D image as 'Ds'
 Ds = [Dxx(:) Dxy(:) Dxz(:) Dyz(:) Dyy(:) Dyz(:) Dzz(:) Dzy(:) Dzz(:)];


 % permute
 Ds = permute(Ds,[2 1]);

 % reshape
 n = numel(Dxx);
 Ds = reshape(Ds,[3 3 n]);

享受吧！

Answer 2

也许你正在寻找这样的东西 -

%%// M and N are the dims of each image and P is the count of images. 
%%// Please not that for 3x3 block processing, you would need to make sure that 
%%// the width of images are divisble by 3; if they are not, consider cropping or padding.
IN = some_MxNxP_data;

%%// In-code cropping, as mentioned earlier
IN = IN(:,1:3*floor(size(IN,2)/3),:);

%%// Final output would be a complex matrix of size Mx(N/3)xP
OUT = zeros(size(IN,1),size(IN,2)/3);

%%// Main calculation part that uses block processing creating 3x3 blocks and using eig3 on each of them 
for k = 1:size(IN,3)
    fun1 = @(block_struct) eig3(block_struct.data);
    OUT(:,:,k) = blockproc(double(IN(:,:,k)),[3 3],fun1);
end

编辑 1

代码

M = 7; %%// Image height, which must be replaced by actual data, 512 in your case
N = 7; %%// Image width, which must be replaced by actual data, 512 in your case
P = 5; %%// Number of images, which must be replaced by actual data, 200 in your case

%%// Your Dxx,Dyx... data, which is created randomly here, for demo
Dxx= rand(M,N,P);
Dyx= rand(M,N,P);
Daz= rand(M,N,P);
Dxy= rand(M,N,P);
Dyy= rand(M,N,P);
Dzy= rand(M,N,P);
Dxz= rand(M,N,P);
Dyz= rand(M,N,P);
Dzz= rand(M,N,P);

voxel_mat = zeros(3,3,M,N,P);
eig_mat = zeros(M,N,3);

for k0 = 1:P
    for k1 = 1:M
        for k2 = 1:N

            voxel_mat(:,:,k1,k2,k0) = [Dxx(k1,k2,k0) Dxy(k1,k2,k0) Dxz(k1,k2,k0); ...
                Dyx(k1,k2,k0) Dyy(k1,k2,k0) Dyz(k1,k2,k0); ...
                Daz(k1,k2,k0) Dzy(k1,k2,k0) Dzz(k1,k2,k0)];

            eig_mat(k1,k2,:,k0) = eig3(voxel_mat(:,:,k1,k2,k0));

        end
    end
end