anyone know how to open .dmi file

Dear all,

I have .dmi file (as attached). Then I try coding as below:

unzip alders.zip
fid = fopen('alders.dmi','rb');
arr = fread(fid,'int8');
fclose(fid);
dim = [64,64,128];
arr = reshape(arr,dim)

But I got error

Error using reshape

Number of elements must not change. Use [] as one of the size inputs to automatically calculate the appropriate size for that dimension.

Anyone can help me?

Answer 1

[Shubham]

Hey @mohd akmal masud

It appears that the error is due to a mismatch between the number of elements in your array and the dimensions you’re trying to reshape it into. The reshape function requires that the total number of elements remains the same before and after reshaping.

unzip alders.zip
fid = fopen('alders.dmi','rb');
arr = fread(fid,'int8');

% Actual Size of the array
disp(size(arr));

      524289           1

% Number of elements in reshaped array
disp(64*64*128);

      524288

% Notice that the number of elements are not same
fclose(fid);
dim = [64,64,128];

% The number of elements should be same for both cases
% Removing the first element of the array.
arr = arr(2:length(arr));
arr = reshape(arr,dim); %No errors now

In order to resolve the error you are facing, either make changes to the dimensions for the reshaped array, or truncate one element to keep the same dimensions. This is to ensure that the number of elements should remain constant after reshaping the array.

I hope this resolves the issue!

Answer 2

[Les Beckham]

There are two issues. One is that your fread command is converting the int8 data to doubles when reading. The other is that the number of bytes in the .dmi file is not equal to 64 * 64 * 128.

unzip alders.zip
fid = fopen('alders.dmi','rb');
arr = fread(fid,'*int8'); %<<< add the * to tell Matlab not to convert the numbers to doubles
fclose(fid);
dim = [64,64,128];
size(arr,1)

ans = 524289

prod(dim)

ans = 524288

size(arr,1) == prod(dim) 

ans = logical
   0

% arr = reshape(arr,dim)

Answer 3

[Sameer]

Hi @mohd akmal masud

The error occured because the total number of elements is not equal to 64 * 64 * 128.

You can verify and adjust as follows:

numElements = numel(arr);
dim1 = 64; 
dim2 = 64; 
% Calculate the third dimension
dim3 = numElements / (dim1 * dim2);
% Check if dim3 is an integer
if mod(dim3, 1) ~= 0
    error('The dimensions do not match the number of elements.');
end
% Reshape the array
arr = reshape(arr, [dim1, dim2, dim3]);
disp(['Reshaped array size: ', num2str(size(arr))]);

Hope this helps!