MATLAB: Hi i have 1×36 cell,each cell contains 7×7 double, i need to divide each 7×7 equally into 4 halves and find max value in each halves,likewise for all 36 cells

digital image processing

help me with matlab code

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yourcellarray = arrayfun(@(~) randi(20, 7), 1:36, 'UniformOutput', false)  %demo data
cellfun(@(m) cellfun(@(quadrant) max(quadrant(:)), ...  max of a quadrant
                     mat2cell(m, ...                    convert matrix in cell into cell of 4 quadrant
                              [ceil(size(m, 1)/2), floor(size(m, 1)/2)], ...
                              [ceil(size(m, 2)/2), floor(size(m, 2)/2)])), ...
        yourcellarray, 'UniformOutput', false) %process each cell

edit: removed the 'UniformOutput', false from the inner cellfun since it's actually not needed. The output is thus a 1x36 cell array of 2x2 matrix instead of a 1x36 cell array of 2x2 cell arrays of scalars.

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MATLAB: 7×7 arithmetic mean filter

You can do this:

windowWidth = 7;
kernel = ones(windowWidth) / windowWidth^2;
outputImage = imfilter(grayImage, kernel);

If you use conv2() you'll need to make sure your input image is not of integer class, so cast it to double first:

outputImage = conv2(double(grayImage), kernel, 'same');

imfilter() does not require casting to double in advance. Also imfilter() does not flip the kernel like convolution does, though for a symmetric filter like this box filter, it doesn't matter if it's flipped or not.

MATLAB: Delete Cells from Cell Array, when size is less than 50% of biggest cell

Here one way:

The given cell data

a={[1,2;3,4;5,6;7,8],[9,10;11,12],[13,14;15,16;17,18]}

Check data

a =
  1×3 cell array
  {4×2 double}    {2×2 double}    {3×2 double}

Get the rows ('1') of all cell elements, if columns, use '2'

cell_sizes=cellfun('size',a,1);

Get the max size of rows and 50% of the row size

max_size=max(cell_sizes);
th=max_size*0.5;

Apply the condtion for rows more than 50% of max size (Get the indices, those are lesser or equal)

idx=find(cell_sizes<=th);

Assign all cell elements with particular indices idx with blanks ([])

a(idx)=[];

Remove all those are blanks cell elements

a(cellfun('isempty',a)) = []

Result:

a =
  1×2 cell array
  {4×2 double}    {3×2 double}

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MATLAB: 7×7 arithmetic mean filter

MATLAB: Delete Cells from Cell Array, when size is less than 50% of biggest cell

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