how to read images one by one

There is multiple images in a folder, but the name is not in order, for example, 01.jpg, 21.jpg, 41.jpg,......101.jpg. How to read these images successively? Thanks very much.

Answer 1

[Stephen23]

If you have a cell array of the names, then use that. If you don't know the names, then use dir to read the names from the directory where they are saved. The MATLAB Wiki gives an complete working example of how to do this:

http://matlab.wikia.com/wiki/FAQ#How_can_I_process_a_sequence_of_files.3F

(Just scroll down a little to find the example using dir.)

One way to sort filenames into alphanumeric order is to download my FEX submission NATSORTFILES:

>> S = dir('*.txt');
>> S.name
ans =
    '1.txt'
ans =
    '10.txt'
ans =
    '2.txt'
>> S = natsortfiles(S); % alphanumeric sort by filename
>> S.name
ans =
    '1.txt'
ans =
    '2.txt'
ans =
    '10.txt'

[rui]

SrcDir=dir('D:\Images\*.jpg'); m=length(SrcDir); for ii=1:m filename=strcat('D:\Images\',SrcDir(ii).name); bw=imread(filename);% Read the image one by one end

This is my code, which can read the images ,following 01.jpg,101.jpg. But I want to read these images following 01.jpg,21.jpg,41.jpg,....101.jpg. Do you have good idea to do it? Thanks very much!

[Joe Perkins]

Unfortunately dir can't find the file pattern for my files. I have used the example straight from the FAQ Image Analyst posted. The images are not labelled in a sequential way. (Particle_3),.. (Particle_11),.. etc

myFolder = 'c:/Users/ezxjp1/Documents/MATLAB/ParticleImages';
% Upload particles, measure size & shape
% Check to make sure that folder actually exists.  Warn user if it doesn't.
if ~isdir(myFolder)
  errorMessage = sprintf('Error: The following folder does not exist:\n%s', myFolder);
  uiwait(warndlg(errorMessage));
  return;
end
% Get a list of all files in the folder with the desired file name pattern.
filePattern = fullfile(myFolder, 'Particle_%d.tif'); % Change to whatever pattern you need.
theFiles = dir(filePattern);

for k = 1 : length(theFiles)
  baseFileName = theFiles(k).name;
  fullFileName = fullfile(myFolder, baseFileName);
  fprintf(1, 'Now reading %s\n', fullFileName);
  imageArray = imread(fullFileName);

[Image Analyst]

Here is what the FAQ correctly says:

% Get a list of all files in the folder with the desired file name pattern.
filePattern = fullfile(myFolder, '*.jpg'); % Change to whatever pattern you need.
theFiles = dir(filePattern);

and here is how you incorrectly modified it:

% Get a list of all files in the folder with the desired file name pattern.
filePattern = fullfile(myFolder, 'Particle_%d.tif'); % Change to whatever pattern you need.
theFiles = dir(filePattern);

Take note that * is a wildcard character and can be used in functions like dir. The "%d" is not a wildcard symbol and is intended to be used in the functions sprintf() or fprintf().

Change the "%d" to "*" and it should work.