Error while reading DICOM images in simple program

I am newbie to MATLAB, I was trying simple example given here. Code:

% Preallocate the 256-by-256-by-1-by-20 image array.
X = repmat(int16(0), [256 256 1 20]);

% Read the series of images.
for p=1:20
   filename = sprintf('brain_%03d.dcm', p);
   X(:,:,1,p) = dicomread(filename);
end

% Display the image stack.
montage(X,[]);

I am getting error as :

Error using montage>validateColormapSyntax (line 339)
An indexed image can be uint8, uint16, double, single, or logical.

Error in montage>parse_inputs (line 259)
        cmap = validateColormapSyntax(I,varargin{2});

Error in montage (line 114)
[I,cmap,mSize,indices,displayRange,parent] = parse_inputs(varargin{:});

Error in main (line 11)
montage(X,[]);

What I am doing wrong here? When I comment montage(), it runs without any error. Thanks for you time.

Answer 1

[Walter Roberson]

If the data signed 16 bit like you seem to indicate, then you will need to use

X = zeros(256, 256, 1, 20);

If the data is unsigned 16 bit then you can use

X = zeros(256, 256, 1, 20, 'uint16');

[Nitinkumar Ambekar]

I tried both lines by adding after repmat(), I am not getting results as expected. By using

X = zeros(256, 256, 1, 20);

I get

And using

X = zeros(256, 256, 1, 20, 'uint16');

I get black image. Thanks @Walter Roberson

[Nitinkumar Ambekar]

I am getting :

Warning: Image is too big to fit on screen; displaying at 50% 
In imshow (line 309)
In montage (line 152)
In main (line 17)

Is this the cause of getting such result?

[Walter Roberson]

You should use the 'Size' option of montage()

montage(X, 'Size', [4 5])

Could you tell me what min(X(:)) and max(X(:)) are?

[Nitinkumar Ambekar]

I tried 'size', getting same output

min(X(:)) is 0

max(X(:)) is 1059

[Nitinkumar Ambekar]

Thanks Walter Roberson, I changed the following and it works now!

$montage(X,[]); %Old which doesnt work
montage(X,'displayrange',[]);

[Walter Roberson]

With that maximum you could use uint16()