How to read input images from the folder sequentially

Hello, In my work I'm giving input as a folder of facial photos which consists of 10 images. The output enhanced images are getting stored in separate folder But the problem is, it is not getting stored in the same order as that of the images passed through input folder. The images are read randomly.

Answer 1

[KALYAN ACHARJYA]

   % Save all images name in a  sequence manner before doing the operation 
   % names for example im1,im2,im3...
   %Save the folder of images in the current directory
   path_directory='folder_name'; % 'Folder name'
   original_files=dir([path_directory '/*.jpg']); 
   for k=1:length(original_files)
      filename=[path_directory '/' original_files(k).name];
      image_orginal=imread(filename);
      % Image read is done
    %%Image Operation as per your work
  end

[Stephen23]

Note that using fullfile is simpler than concatenating strings and file separators.

[KALYAN ACHARJYA]

Agree @Stephan Sir, Thank u

[Jan]

Using fullfile is safer as [a, '/', b], because it considers existing file separators.

[Halee Scott]

Where would fullfile be used in the script then? Sorry I am new to coding and adapting this to create a for loop that changes file types (.oib to .tiff) and saves the new files in a different folder.

[Stephen23]

"Where would fullfile be used in the script then?"

https://www.mathworks.com/matlabcentral/answers/393578-how-to-read-input-images-from-the-folder-sequentially#answer_332825

Answer 2

[Stephen23]

Presumably the filenames have numbers in them, and you are getting them listed not in numeric order...One solution is to download my FEX submission natsortfiles, which was written to solve that exact problem:

https://www.mathworks.com/matlabcentral/fileexchange/47434-natural-order-filename-sort

There are plenty of examples in the Mfile, in the online description, and in the HTML documentation, so you should not have any problems using it. You will probably want something like this:

D = 'path of the folder where the files are';
S = dir(fullfile(D,'*.txt'));
F = natsortfiles({S.name});
for k = 1:numel(F)
    im = imread(fullfile(D,F{k}))
    ...
end

[Manuella Juwita]

Hello Sir, can I ask how to read a video file and save it to multiple frames in numerical order? Because I keep getting back random frames not in order of the video progression, my code is this:

vid = VideoReader('vid.mp4');
numFrames = vid.NumberofFrames;
n = numFrames;
for i=1:1:n
    frames = read(vid,i);
    imwrite(frames,['C:mydirectory\'int2str(i),'.jpg']);
    im(i)=image(frames);
end

Thanks in advance

[Stephen23]

"Hello Sir, can I ask how to read a video file and save it to multiple frames in numerical order?"

They already are saved in numeric order.

The problem is that the OS does not sort them alphanumerically when returning a list of files, e.g. when queried via dir. In order to get the filenames sorted in numeric order, you basically have two choices:

1. use a tool that can sort them into alphanumeric order when importing or processing the files, e.g. by downloading my FEX submission natsortfiles and following its examples.
2. use adequate leading zeros so that a character sort gives the expected order. This would be a simple choice for your code because you know the total number of frames, e.g.:

D = 'C:mydirectory';
V = VideoReader('vid.mp4');
N = V.NumberofFrames;
Z = 1+floor(log10(N));
for k = 1:N
    I = read(V,k);
    F = sprintf('%0*u.jpg',Z,k);
    imwrite(I,fullfile(D,F));
end

[Manuella Juwita]

Thank you very much for the prompt reply, Stephen. It was really helpful :)

[Manuella Juwita]

Hello,

I want to ask, how to use natsortfiles to sort alphanumerically overlaying plots in one figure? I find it difficult to match one plot to another because they have different directories and names.

[Jan]

@Manuella Juwita: What are "alphanumerically overlaying plots in one figure"? Plots do not have directories.