How to read images sequentially from a folder?

조회 수: 16 (최근 30일)
Zara Khan
Zara Khan 2022년 7월 5일
편집: Stephen23 2022년 7월 6일
sourcefolder = 'E:\images';
filepattern = fullfile(sourcefolder, '*.png');
outputfolder = 'E:\images2';
srcFiles = dir(filepattern);
numImages = length(srcFiles);
for k = 1 : numImages
inputfilename = fullfile(sourcefolder, srcFiles(k).name);
outputfilename = fullfile(outputfolder, sprintf('histo_%d.png',k));
.....
....
....
end
My folder containing 1400 images. Whenever I am reading images using the above code and after performing any image processing its not happening sequentially. How can read images by one by one maintaing the sequence and can write to them by maintaining the same order.
  댓글 수: 2
Chunru
Chunru 2022년 7월 5일
you need to sort the srcFiles first according to your need.
Zara Khan
Zara Khan 2022년 7월 5일
how to do that

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채택된 답변

Stephen23
Stephen23 2022년 7월 5일
편집: Stephen23 2022년 7월 6일
You can download the file NATSORTFILES by clicking the big blue download button here:
then unzip the file onto the MATLAB search path (e.g. into the current directory), and then use it like this:
srcFiles = dir(filepattern);
srcFiles = natsortfiles(srcFiles);

추가 답변 (2개)

Pooja Kumari
Pooja Kumari 2022년 7월 5일
편집: Pooja Kumari 2022년 7월 5일
Dear Zara Khan,
It is my understanding that you want to access the images present in the folder sequentially and after performing some operations, you want to store the output image in ‘output filename’.
But the issue you were facing is that when you are reading images using the provided code and after getting the input file name and performing some image processing, you were not getting the output sequentially is because the files stored in input file name is not sequential.
You can refer to the updated code given below:
sourcefolder = 'E:\images'; %path of your source folder
filepattern = (fullfile(sourcefolder, '*.png'));
srcFiles = dir(filepattern);
numImages = length(srcFiles);
outputfolder = 'E:\images2';
for i= 1: numel(srcFiles)
I =(imread(strcat(sourcefolder,'/',srcFiles(i).name)));
outputfilename = fullfile(outputfolder, sprintf('histo_%d.png',i));
.....
....
...
end
Please find attached a reference code for the above issue you were facing:
% I have 50 images named numerically '15_1_s', '15_2_s', ... '15_50_s' but
% the order in which these files are stored is shown in the image below:
path = '/MATLAB Drive/CV_Assignment2/dd/dd';
folder = (path);
files = dir(fullfile(folder,'*.jpg'));
nfiles = length((files));
mkdir(['Outputfolder',sprintf('%d',outputfolder)]); % similar to outputfolder.
for i= 1: numel(files)
I =(imread(strcat(path,'/',files(i).name)));
imwrite(imgx,strcat(path_output,'/',files(i).name));
%output will be stored sequentially .
end
For more information on how to sort files stored in a directory , you can refer to the below link:
You can refer to this file, if you want to sort the input files naturally:
Sincerely,
Pooja Kumari
  댓글 수: 1
Zara Khan
Zara Khan 2022년 7월 6일
Thank you madam for very nice explanation of my problem. Thanks once again for the response. I have used the natsortfiles in this case and its working well till now. I will also give a try of your answer also. Thanks.

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Chunru
Chunru 2022년 7월 5일
편집: Chunru 2022년 7월 5일
% create some files
system('touch a.png');
system('touch c.txt');
pause(1) % make sure b is newer in datenum
system('touch b.txt');
pause(.5)
% get the files
f = dir('*.*');
{f.name}
ans = 1×5 cell array
{'.'} {'..'} {'a.png'} {'b.txt'} {'c.txt'}
% sort according to name
[~, idx] = sort({f.name})
idx = 1×5
1 2 3 4 5
fname = {f(idx).name}
fname = 1×5 cell array
{'.'} {'..'} {'a.png'} {'b.txt'} {'c.txt'}
% sort according to datetime
[~, idx] = sort([f.datenum])
idx = 1×5
2 3 5 1 4
fname = {f(idx).name}
fname = 1×5 cell array
{'..'} {'a.png'} {'c.txt'} {'.'} {'b.txt'}
  댓글 수: 6
Zara Khan
Zara Khan 2022년 7월 5일
편집: Zara Khan 2022년 7월 5일
Sorted by names . Like they are img1, img2,......img1400. I have tried with natsortfiles also. But the function is telling undefined
Walter Roberson
Walter Roberson 2022년 7월 5일
You need to use the Add-On Explorer to install natsortfiles .

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