How to divide an image into 8 equal parts ?

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Sneha Suresh 2015-8-26

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回答： Jordan Kennedy 2021-5-1

I am working on medical imaging and I have to segment an image into 8 equal parts.Can anyone help me with the code?

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Adam 2015-8-26

Equal in what way?

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Answer 1

Walter Roberson 2015-8-26

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This is not always possible. In order to divide an image into 8 equal parts, the number of elements of the array must be divisible by 8. If the image is grayscale then the third dimension is 1, which will not help the number be divisible by 8; if the image is color then the third dimension is 3, which will not help the number be divisible by 8. Therefore the produce of the number of row and number of colors must be divisible by 8. And that is certainly not always the case, since the number of rows and number of columns could both be odd.

The easiest case would be if the number of rows or the number of columns was exactly divisible by 8, as then you could divide it up into 8 pieces along that dimension.

If the neither the rows nor columns are exactly divisible by 8, you can still create 8 equal pieces if either the rows or columns is divisible by 4 and the other dimension is divisible by 2

If the number of elements is divisible by 8, then one way to divide into 8 equal pieces for grayscale images would be:

pieces = cell(8,1);
nel = numel(YourImage);
nel8 = nel / 8;
for K = 1 : 8
  pieces{K} = YourImage((K-1)*nel8 + 1 : K * nel8);
end

The resulting pieces will be column vectors. You never said that the pieces had to be meaningful, only that they be equal. If the number of columns happens to be divisible by 8 then those pieces could be reshaped to be equal vertical strips, but not otherwise.

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Answer 2

Jordan Kennedy 2021-5-1

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Divide up image by specifying number of rows and columns you want and save off sub images.

filename=' path to image image.tif';
E = imread(filename);
[row, col, ~] = size(E);
num_img_h = 6; %define number col
num_img_v = 3; %number of rows
row_breaks = round(linspace(1,row,num_img_v+1),0)
col_breaks = round(linspace(1,col,num_img_h+1),0)
loop = 1
for iter1 = 1:num_img_v
    iter1
    for iter2 = 1:num_img_h
        iter2
        imwrite(E(row_breaks(iter1):row_breaks(iter1+1),col_breaks(iter2):col_breaks(iter2+1),1:3),['temp', num2str(loop), '.tiff']);
        loop = loop + 1
    end
end