I have a folder with 1500 images. I need to process the first 200 images(ie, 1 to 200). I used for loop it. But when i run the code i starts from 1,2,3 ... 100. then instead if going for 101th image, its value changes to 1001 , 1002... and so on.

start:1
stop:200
for i = start : stop
XX
end

But i need to continue from 101, 102,... after 100. Kindly help me identify the problem.

Answer 1

[Stephen23]

You have discovered ASCII sorting is not the same as human sorting.

The easiest solution is to use my FEX submission natsortfiles. It fixes the order of an ASCII sort to take into account any numeric values in the strings. Note that it requires the file natsort to work!

It simply sorts a cell array of filenames into the order you want:

S = dir('*.jpg');
S = natsortfiles(S);
for k = 1:200 % first 200 files
    F = S(k).name;
    ... your code
end

Note that this answer assumes that your files are sequentially numbered without any gaps. If this is not true, then you need to give more information on the filenaming logic.

[jeffin]

sir, the problem with me is the following,

My code is as follows,

srcFiles = dir('E:\New Folder\*.tif'); % the folder in which images exists
start = 1 ;
end = 200;
for i = start : end
    filename = strcat('E:\New Folder\',srcFiles(i).name);    
    I = imread(filename);
    figure, imshow(I);
end

for

 i = 1  => srcFiles(i).name = 1.tif
 i = 2  => srcFiles(i).name = 2.tif
 i = 3  => srcFiles(i).name = 3.tif

and so on... but when

 i = 101  => srcFiles(i).name = 1001.tif and
 i = 102  => srcFiles(i).name = 1002.tif

But i need this to read 101.tif and 102.tif for i=101 and 102.

Kindly help me.

[Stephen23]

Here is one way of solving your task using my answer:

P = 'E:\New Folder';
S = dir(fullfile(P,'*.tif'));
S = natsortfiles(S);
for k = 1:200
    F = fullfile(P,S(k).name);    
    I = imread(F);
    figure;
    imshow(I);
end

Note:

• you will need to download NATSORTFILES.
• I changed the loop variable from i to k, because in MATLAB i is the imaginary unit.
• I used fullfile to create the path strings, which is much more robust than using strcat.

Answer 2

[Image Analyst]

Try these:

http://blogs.mathworks.com/pick/2014/12/05/natural-order-sorting/

http://blogs.mathworks.com/pick/2006/09/11/file1-file10-file2-sorting-problem-solved/

[Stephen23]

Thank you for the links! I think both were picked for PotW, but there are a few differences:

Note that natsorfiles correctly considers the file-names and file-extensions separately.

[Image Analyst]

Stephen, you should notice that first link I gave actually talks about your submission as the "Pick of the Week".