change matrix from 3D TO 2D

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abbas hasan
abbas hasan 2012-12-6
评论： Mattias Gothberg 2022-5-20
i have 3d matrix (512x512x3) i want transform to 2d matrix (512x512)
  1 个评论
Mattias Gothberg
Mattias Gothberg 2022-5-20
check out squeeze comand after apropiate processing or selection

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回答（2 个）

Thomas
Thomas 2012-12-6
编辑：Thomas 2012-12-6
Your matrix has 512*512*3=786432 elements.. to reshape you need to keep the number of elements the same.. That means you cannot reshape if you want just 512*512 elements without losing elements or data..
However if you want to access only the first dimension of your matrix (a) you use some thing like a(:,:,1)
If your data is an image data and it has the three dimension r,g,b you can covert it to grayscale (using im2bw)which should give you a matrix of 512*512
Example for my color image 1.jpg
ii=imread('1.jpg');
size(ii)
ans =
551.00 1024.00 3.00
out=im2bw(ii); % convert to blackwhite
size(out)
ans =
551.00 1024.00
Wayne King
Wayne King 2012-12-6
编辑：Wayne King 2012-12-6
You have to select one "page" of the 3D matrix, which one do you want?
X = randn(512,512,3);
Y = X(:,:,1);
Or you can form some function of the 3 pages, not sure what you want. For example:
X = randn(512,512,3);
Y = mean(X,3);

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