how to use imwrite in matlab?

how to use imwrite in matlab?The file which that we are specifying to write,should it be already be created in the folder?

Answer 1

[Walter Roberson]

No. If the file does not already exist then it will be created. If the file does already exist then it will be overwritten.

[Anushka]

But Sir it shows the error Can't open file "Compressed Image.bmp" for writing. You may not have write permission.

[Walter Roberson]

Check your directory. It is not allowed to write into one of the subdirectories of the MATLAB installation.

[Abdoo]

Notice, Check the file is close before you go on, because can't write data and file is open.

[Guillaume]

Note: to close all open file handles:

 fclose all

Answer 2

[B.k Sumedha]

imwrite(A,filename,fmt);

This is the general format of imwrite. Its not necessary that image needs to be present in ur folder. Where A is ur image which u want to save,specify the file name and its format. For ex:

imwrite(im_DIF,'Image difference.bmp','bmp');

[Anushka]

But Sir it shows the error Can't open file "Compressed Image.bmp" for writing. You may not have write permission.

[B.k Sumedha]

Do u have the same filename existing in the current folder? Have u specified the correct path where the image needs to be written.

If ur saving it in a new directory then be sure that the directory exists in the current path.

[mima zebouchi]

but what about imrwite of dicom images plz i need answer

[Walter Roberson]

You cannot use imwrite() to write dicom images. You need dicomwrite()

Answer 3

[Alejandro Cruz Rubio]

Anyone Know how to save a block of images with imwrite?

[Walter Roberson]

Could you expand on your question ?

[Alejandro Cruz Rubio]

Yes, sorry.

I have 45 blocks of 256x256 resolution each block in a same image, tha is, I have an image with 45 blocks and I need to save each block in a different image. Do you know how to do that? I am using imwrite function but I only get the first block and I need to save all of them as a different image each of them.

[Walter Roberson]

If the blocks are a cell array, then

for K = 1 : numel(YourImageCell)
    filename = sprintf('Output_block_%d.png', K);
    imwrite(YourImageCell{K}, filename);
end

[Guillaume]

I'd recommend %02d instead of plain %d in the format string of sprintf just so that when you list the files the alphabetical order and the numerical order match.

[Alejandro Cruz Rubio]

I have a cell array whose cells contains subarrays, that is, I`ve used mat2cell function and if I use the code above I get an error message indicating "Unable to determine the file format from the file name" in imwrite function. After that, I extract the array of numbers out of the cell and I get one simple image with all the blocks. The code is:

wholeBlockR = floor(rows / blockSizeR);
blockVectorR = [blockSizeR * ones(1, wholeBlockR), rem(rows, blockSizeR)];
wholeBlockCols = floor(columns / blockSizeC); 
 blockVectorC = [blockSizeC * ones(1, wholeBlockCols), rem(columns, blockSizeC)];
arrayCells=mat2cell(Image,blockVectorR, blockVectorC); 
plotIndex=1;
 numPlotsR = size(arrayCeldas, 1);
 numPlotsC = size(arrayCeldas, 2); 
 for r = 1 : numPlotsRow
            for c = 1 : numPlotsCol
             subplot(numPlotsRow, numPlotsCol, plotIndex);
            block = arrayCells{r,c};
            imshow(block); % In this moment I show all the blocks in a simple image and each              %block is an image.
            close
            plotIndex = plotIndex + 1;
            end
    end
% In this point I need to extract each block and save it as an image.
for k=1:numel(arrayCells)
     filename = sprintf('Output_block_%d.png', K);
   imwrite(arrayCells{k}, filename); % in this point I get the error shown  % above
end

[Walter Roberson]

Be careful, you switched from for k with lower-case K, to using upper-case K in the filename.

Is it possible that you are using a very old MATLAB? Such as MATLAB 5.x or MATLAB 6.0 ?

[Alejandro Cruz Rubio]

My version of Matlab is 2018b. Yeah I solve the problem with K and k and I get the same error. And if I use the arrayCells inside of for, that is:

for k=1:numel(arrayCells)
     filename = sprintf('Output_block_%d.png', K);
   imwrite(arrayCells{k}, filename); 
end

I get this error: "Error using imwrite (line 433)

Unable to determine the file format from the file name" because I use arrayCells but if I use "block" I don´t have any problem but I don´t get my goal

[Rik]

With the code you show you actually haven't fixed the code yet. The code below should work a lot better.

for k=1:numel(arrayCells)
    filename = sprintf('Output_block_%d.png', k);%<--- lower case k, instead of upper case K
    imwrite(arrayCells{k}, filename); 
end

Answer 4

[kass]

for k=1:numel(I)
 imwrite(I{k}, ['filename' num2str(k) '.pgm']);
 end
%I is arraycells