MATLAB: Mat2Cell error when splitting an image up into smaller images

mat2cell

Hello, i have a large Image (3200 x 14444 pixels). I want to split it into subimages. Im using mat2cell but Im getting the error as shown below.

blockSizeRow=512
blockSizeCol=256

function blockImages = splitImageIntoBlocks(image, blockSizeRow, blockSizeCol)
% blockSizeRow: Rows in block
% blockSizeCol: Columns in block
[nrows, ncols] = size(image);
% Calculate size of each block by rows and columns
nBlocksRow = floor(nrows / blockSizeRow);
nBlocksCol = floor(ncols / blockSizeCol);
rowDist = [blockSizeRow * ones(1, nBlocksRow-1), rem(nrows, nBlocksRow) + blockSizeRow];
colDist = [blockSizeCol * ones(1, nBlocksCol-1), rem(ncols, nBlocksCol) + blockSizeCol];
blockImages = mat2cell(image, rowDist, colDist);

Error using mat2cell (line 89)
Input arguments, D1 through D2, must sum to each dimension of the input matrix size, [3200  14444].

Best Answer

function blockImages = splitImageIntoBlocks(image, blockSizeRow, blockSizeCol)
% blockSizeRow: Rows in block
% blockSizeCol: Columns in block
[nrows, ncols] = size(image);
% Calculate size of each block by rows and columns
nBlocksRow = floor(nrows / blockSizeRow);
nBlocksCol = floor(ncols / blockSizeCol);
rowDist = [blockSizeRow * ones(1, nBlocksRow), mod(nrows, nBlocksRow)];
colDist = [blockSizeCol * ones(1, nBlocksCol), mod(ncols, nBlocksCol)];
%check for case of file image divisible into blocks
if rowDist(end) == 0; rowDist(end) = []; end
if colDist(end) == 0; colDist(end) = []; end
blockImages = mat2cell(image, rowDist, colDist, size(image,3));

Related Solutions

MATLAB: Can anyone say how to divide an image in 6 parts

This is for dividing a image into four equal parts

Yes, and it is horrible! If you start numbering variables you are doing it wrong. A loop or a vectorised method is always better. In your case:

%img: input image
nrows = 2;   %can be whatever you want

ncols = 3;   %can be whatever you want
%some checks first
assert(mod(size(img, 1), nrows) == 0, 'number of rows of image not divisibly by nrows');
assert(mod(size(img, 2), ncols) == 0, 'number of columns of image not divisibly by ncols');
%now divide the image
subimages = mat2cell(img, ones(1, nrows) * size(img, 1)/nrows, ones(1, ncols) * size(img, 2)/ncols, 1)
%all done!

subimages{n} is the same as your original In with the advantage that you can loop over it if needed.

MATLAB: Can anybody please help me to do the following

You can use mat2cell to divide a matrix into submatrices:

img = uint8(randi([0 255], 206, 100, 3)); %for example

n = 10; %for example
rowdist = n * ones(1, ceil(size(img, 1) /  n));
rowdist(end) = size(img, 1) - sum(rowdist(1:end-1)); %in case n is not a divisor of the image height
coldist = n * ones(1, ceil(size(img, 2) /  n));
coldist(end) = size(img, 2) - sum(coldist(1:end-1)); %in case n is not a divisor of the image width
subimgs = mat2cell(rowdist, coldist, size(img, 3))

To convert the cell array of matrices to a cell array of vectors:

subimgv = cellfun(@(m) m(:), subimgs, 'UniformOutput', false)

Best Answer

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MATLAB: Can anybody please help me to do the following

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