how to resolve index exceeds matrix dimensions in matlab?

i am trying to read series of dicom images from a folder named as series 8.below is code to read series of dicom images from a particular folder.i am getting

error index exceeds matrix dimensions at 
info = dicominfo(fullfile(fileFolder,fileNames{1})).

----

clear all;
close all;
clc;
fileFolder = fullfile(pwd, 'series 8');
files = dir ( fullfile (fileFolder, '*.dcm'));
fileNames = {files.name};

%examine file header (metadata , from dicom stack)

info = dicominfo(fullfile(fileFolder,fileNames{1}))

%extract size info from metadata
voxelsize = [info.PixelSpacing;info.SliceThickness];

%read one file to get size
I = dicomread(fullfile(fileFolder,fileNames{1}))
classI = class(I);
sizeI = size(I);
numImages = length(fileNames);

%read slice images populate 3d matrix
hWaitBar = waitbar(0,'reading dicom files');

%create array
mri= zeroes(info.rows , info.columns , numImages , classI )
for i=length(fileNames):-1:1
    fname = fullfile(fileFolder, fileNames{i});
    mri(:,:,i) = unit16(dicomread(fname));
    waitbar((length(fileNames)-i+1)/length(fileNames))
end

delete(hWaitBar);

Answer 1

[Walter Roberson]

You would get that error if there is no 'series 8/*.dcm' relative to the starting directory. Your code assumes that at least one file name was returned, without testing for that being true.

[santosh patil]

@Walter Roberson but there are dicom files in series 8 folder..

[Stephen23]

What does size(fileNames) show?

Answer 2

[Image Analyst]

Normal debugging procedures would suggest you do it in two or more steps:

fileFolder = fullfile(pwd, 'series 8')
filePattern = fullfile (fileFolder, '*.dcm')
files = dir(filePattern);
fileNames = {files.name};
if isempty(fileNames)
  message = sprintf('There are no *.dcm files in the folder:\n%s', fileFolder);
  uiwait(warndlg(message));
  return;
end
% If we get here, there is at least one file.
% Examine file header (metadata , from dicom stack) from the very first file.
fullFileName = fullfile(fileFolder, fileNames{1})
if exist(fullFileName, 'file')
    successMessage = sprintf('File does indeed exist:\n%s', fullFileName);
    uiwait(helpdlg(successMessage ));
    info = dicominfo(fullFileName)
else
    warningMessage = sprintf('File does NOT exist:\n%s', fullFileName);
    uiwait(warndlg(warningMessage));
end

Now what do you see?

EDIT I edited it to add a popup warning message if there are no dcm files present in the folder.

More related code samples are in the FAQ http://matlab.wikia.com/wiki/FAQ#How_can_I_process_a_sequence_of_files.3F, like how to process all the files instead of just the first one.