How split an image into four parts?

I have 2x10 cell array each cell contains 224x896 double, I want to split each image inside the cells to 224x224

Answer 1

[Voss]

% since I don't have your cell array, I make one up:
C = repmat({randi([0 255],224,896)},2,10)

C = 2×10 cell array
    {224×896 double}    {224×896 double}    {224×896 double}    {224×896 double}    {224×896 double}    {224×896 double}    {224×896 double}    {224×896 double}    {224×896 double}    {224×896 double}
    {224×896 double}    {224×896 double}    {224×896 double}    {224×896 double}    {224×896 double}    {224×896 double}    {224×896 double}    {224×896 double}    {224×896 double}    {224×896 double}

% split each matrix in C into 4:
C_new = cellfun(@(x)mat2cell(x,224,224*ones(1,4)),C,'UniformOutput',false)

C_new = 2×10 cell array
    {1×4 cell}    {1×4 cell}    {1×4 cell}    {1×4 cell}    {1×4 cell}    {1×4 cell}    {1×4 cell}    {1×4 cell}    {1×4 cell}    {1×4 cell}
    {1×4 cell}    {1×4 cell}    {1×4 cell}    {1×4 cell}    {1×4 cell}    {1×4 cell}    {1×4 cell}    {1×4 cell}    {1×4 cell}    {1×4 cell}

% each cell of C_new contains a 1x4 cell array containing the 4 224x224 matrices:
C_new{1,1}

ans = 1×4 cell array
    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}

C_new{2,1}

ans = 1×4 cell array
    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}

% etc.

[Bajdar Nouredine]

dear @Voss thank so much, my problem solved but not completely, now, how could I restrict first images in row 1 (C_new) (i.e in C_new row 1, first cell, first 224x224 with second cell,first 224x224,with, third cell,first 224x224.... till end)

[Image Analyst]

@Bajdar Nouredine what do you mean by "restrict"? As you can see the individual cells do contain images of that size. What form do you prefer the images in? Why are you using a cell array anyway?

[Bajdar Nouredine]

dear @Image Analyst

in C_new as mentioned by @Voss a cell array contains a 1x4 cell array containing 4 224x224 matrices, I want to create 4 new cell arrays 2x10 as follow:

1st cell array (2x10) contains only first 224*224 s

2nd cell array (2x10) contains only second 224*224 s

3rd cell array (2x10) contains only third 224*224 s

4th cell array (2x10) contains only fourth 224*224 s

[Voss]

Instead of 4 separate variables, how about a single cell array of size 2x10x4?

% (same as before) generation of random data:
C = repmat({randi([0 255],224,896)},2,10)

C = 2×10 cell array
    {224×896 double}    {224×896 double}    {224×896 double}    {224×896 double}    {224×896 double}    {224×896 double}    {224×896 double}    {224×896 double}    {224×896 double}    {224×896 double}
    {224×896 double}    {224×896 double}    {224×896 double}    {224×896 double}    {224×896 double}    {224×896 double}    {224×896 double}    {224×896 double}    {224×896 double}    {224×896 double}

% (same as before) split each matrix in C into 4:
C_new = cellfun(@(x)mat2cell(x,224,224*ones(1,4)),C,'UniformOutput',false)

C_new = 2×10 cell array
    {1×4 cell}    {1×4 cell}    {1×4 cell}    {1×4 cell}    {1×4 cell}    {1×4 cell}    {1×4 cell}    {1×4 cell}    {1×4 cell}    {1×4 cell}
    {1×4 cell}    {1×4 cell}    {1×4 cell}    {1×4 cell}    {1×4 cell}    {1×4 cell}    {1×4 cell}    {1×4 cell}    {1×4 cell}    {1×4 cell}

% rearrange the contents of C_new:
C_newer = permute(reshape([C_new{:}],4,2,[]),[2 3 1])

C_newer = 2×10×4 cell array
C_newer(:,:,1) = 

    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}
    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}


C_newer(:,:,2) = 

    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}
    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}


C_newer(:,:,3) = 

    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}
    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}


C_newer(:,:,4) = 

    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}
    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}

So, C_newer{i,j,k} is the matrix stored in the kth cell of C_new{i,j}, i.e., C_new{i,j}{k}.

Put another way, C_newer{i,j,k} is the kth quarter of the original C{i,j}.

% Verification:
all_ok = true;
for i = 1:2
    for j = 1:10
        for k = 1:4
            if ~isequal(C_newer{i,j,k}, C_new{i,j}{k}, C{i,j}(:,(end/4)*(k-1)+1:(end/4)*k))
                all_ok = false;
                break
            end
        end
        if ~all_ok, break; end
    end
    if ~all_ok, break; end
end
if all_ok
    disp('Looks good!');
else
    disp('Something''s wrong!');
end

Looks good!

(If you really want 4 separate variables, you can easily do that:)

C_newer_1 = C_newer(:,:,1)

C_newer_1 = 2×10 cell array
    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}
    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}

C_newer_2 = C_newer(:,:,2)

C_newer_2 = 2×10 cell array
    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}
    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}

C_newer_3 = C_newer(:,:,3)

C_newer_3 = 2×10 cell array
    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}
    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}

C_newer_4 = C_newer(:,:,4)

C_newer_4 = 2×10 cell array
    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}
    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}

[Bajdar Nouredine]

thank you @Voss @Image Analyst @Matt J

Answer 2

[Matt J]

Using mat2tiles from this FEX download,

https://www.mathworks.com/matlabcentral/fileexchange/35085-mat2tiles-divide-array-into-equal-sized-sub-arrays

C(1:2,1:10)={rand(224,896)}; %hypothetical input

A= mat2tiles( cell2mat(C), [224,224]);

A=permute(reshape(A,2,4,10),[1,3,2]) %final result

A = 2×10×4 cell array
A(:,:,1) = 

    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}
    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}


A(:,:,2) = 

    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}
    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}


A(:,:,3) = 

    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}
    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}


A(:,:,4) = 

    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}
    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}    {224×224 double}