在MATLAB中调整3Dmatrix（图像）的大小

我有一个三维matrix（MxNxK），并想调整它（M'xN'xK'）（如imresize在matlab中）。 我正在使用图像金字塔，但其结果不是很准确，需要一个更好的。 任何解决scheme

Answer 1

你可以使用interp3 （因为你想插入3D数据）：

 im=rand(2,3,4); %% input image ny=3;nx=3;nz=5; %% desired output dimensions [yxz]=... ndgrid(linspace(1,size(im,1),ny),... linspace(1,size(im,2),nx),... linspace(1,size(im,3),nz)); imOut=interp3(im,x,y,z); 

Answer 2

查看image processing工具箱中三维MRI数据集的探索切片示例。 它看起来比实际上更复杂。 根据这个例子，你也可以很容易地select插值方法。 要调整体积isotrope由x ，你必须使用类似的东西（我没有testing它）：

 T = maketform('affine',[x 0 0; 0 x 0; 0 0 x; 0 0 0;]); R = makeresampler({'cubic','cubic','cubic'},'fill'); ImageScaled = tformarray(Image,T,R,[1 2 3],[1 2 3], round(size(Image)*x),[],0); 

如果您正在处理二进制图像/体积，则将“立方体”插值更改为“最接近”可能会更好。

Answer 3

这里是我们在kWave工具箱中使用的resize函数。

 function mat_rs = resize(varargin) %RESIZE Resize a matrix. % DESCRIPTION: % Resize a matrix to a given size using interp2 (2D) or interp3 % (3D). % Use interpolation to redivide the [0,1] interval into Nx, Ny, Nz % voxels, where 0 is the center of first voxel, and 1 is the center % of the last one. % % USAGE: % mat_rs = resize(mat, new_size) % mat_rs = resize(mat, new_size, interp_mode) % % INPUTS: % mat - matrix to resize % new_size - desired matrix size in elements given by [Nx, Ny] in % 2D and [Nx, Ny, Nz] in 3D. Here Nx is the number of % elements in the row direction, Ny is the number of % elements in the column direction, and Nz is the % number of elements in the depth direction. % % OPTIONAL INPUTS: % interp_mode - interpolation mode used by interp2 and interp3 % (default = '*linear') % % OUTPUTS: % mat_rs - resized matrix % check the inputs for release B.0.2 compatability if length(varargin{2}) == 1 && nargin >= 3 && length(varargin{3}) == 1 % display warning message disp('WARNING: input usage deprecated, please see documentation.'); disp('In future releases this usage will no longer be functional.'); % recursively call resize with the correct inputs if nargin == 3 mat_rs = resize(varargin{1}, [varargin{2}, varargin{3}]); else mat_rs = resize(varargin{1}, [varargin{2}, varargin{3}], varargin{4}); end return end % update command line status disp('Resizing matrix...'); % assign the matrix input mat = varargin{1}; % check for interpolation mode input if nargin == 2 interp_mode = '*linear'; elseif nargin ~= 3 error('incorrect number of inputs'); else interp_mode = varargin{3}; end % check inputs if numDim(mat) ~= length(varargin{2}) error('resolution input must have the same number of elements as data dimensions'); end switch numDim(mat) case 2 % extract the original number of pixels from the size of the matrix [Nx_input, Ny_input] = size(mat); % extract the desired number of pixels Nx_output = varargin{2}(1); Ny_output = varargin{2}(2); % update command line status disp([' input grid size: ' num2str(Nx_input) ' by ' num2str(Ny_input) ' elements']); disp([' output grid size: ' num2str(Nx_output) ' by ' num2str(Ny_output) ' elements']); % check the size is different to the input size if Nx_input ~= Nx_output || Ny_input ~= Ny_output % resize the input matrix to the desired number of pixels mat_rs = interp2(0:1/(Ny_input - 1):1, (0:1/(Nx_input - 1):1)', mat, 0:1/(Ny_output - 1):1, (0:1/(Nx_output - 1):1)', interp_mode); else mat_rs = mat; end case 3 % extract the original number of pixels from the size of the matrix [Nx_input, Ny_input, Nz_input] = size(mat); % extract the desired number of pixels Nx_output = varargin{2}(1); Ny_output = varargin{2}(2); Nz_output = varargin{2}(3); % update command line status disp([' input grid size: ' num2str(Nx_input) ' by ' num2str(Ny_input) ' by ' num2str(Nz_input) ' elements']); disp([' output grid size: ' num2str(Nx_output) ' by ' num2str(Ny_output) ' by ' num2str(Nz_output) ' elements']); % create normalised plaid grids of current discretisation [x_mat, y_mat, z_mat] = ndgrid((0:Nx_input-1)/(Nx_input-1), (0:Ny_input-1)/(Ny_input-1), (0:Nz_input-1)/(Nz_input-1)); % create plaid grids of desired discretisation [x_mat_interp, y_mat_interp, z_mat_interp] = ndgrid((0:Nx_output-1)/(Nx_output-1), (0:Ny_output-1)/(Ny_output-1), (0:Nz_output-1)/(Nz_output-1)); % compute interpolation; for a matrix indexed as [M, N, P], the % axis variables must be given in the order N, M, P mat_rs = interp3(y_mat, x_mat, z_mat, mat, y_mat_interp, x_mat_interp, z_mat_interp, interp_mode); otherwise error('input matrix must be 2 or 3 dimensional'); end