Read DICOM files and create a Montage

Hi all, I'm quiet new to MatLab and started doing some DICOM Image processing tasks for my project. I am following this Mathworks article to make a montage as a simple exercise. But it gives me an error though I follow the same code segments.

The simple code is

% 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('DICOM/brain_%03d.dcm', p);
 X(:,:,1,p) = dicomread(filename);
end
% Display the image stack.
montage(X,[])

It gives me the error,

>> ReadDicomFiles
Error using montage>validateColormapSyntax (line 334)
An indexed image can be uint8, uint16, double, single, or logical.

Error in montage>parse_inputs (line 254)
cmap = validateColormapSyntax(I,varargin{2});

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

Error in ReadDicomFiles (line 9)
montage(X,[])

I'm using the same dataset they provided. What will be the reason?

Answer 1

[Stalin Samuel]

s = dicomread('IM-0001-0001.dcm');%read one image to find the size
[r c] = size(s);
X = repmat(double(0), [r c 1 9]);

for p=1:9
   filename = sprintf('IM-0001-000%d.dcm', p);
   X(:,:,1,p) =double(dicomread(filename));
end

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

[Praz Sam]

Thanks a lot for your answer. It worked. But I had to change the contrast manually to see the result.Anyway it's great if you can explain a little bit about this. Thanks in advance.

[Daniel Bridges]

I had the same error Praz did, using my own DICOM files, and I think it was from the data being int16 instead of uint16: Wrapping dicomread(filename) in the uint16 or double function gets montage to work.

It seems I should use uint16 rather than double to keep the data as 16-bit rather than convert it to 64-bit unnecessarily.

[Ryan Harris]

So i'm getting an error for the very last line montage(x,[]). Why do you think this is?