How use imread in a loop

Hello everyone,

i am trying to use imread to read multiple images in a for loop.

path='Z:\collect_data';

for t=1:length(nan_rows)

image_test=imread([path,'nan_rows' (t)]);

%further coding

end

the 'nan_rows' here is a string array.

I want to read the images which the file names are stored in the array.

Does anyone know how to do it?

Thanks a lot in advance!

[DGM]

There are many, many examples around. This is a handful from the first page of search results.

https://matlab.fandom.com/wiki/FAQ#How_can_I_process_a_sequence_of_files?

https://www.mathworks.com/matlabcentral/answers/57446-faq-how-can-i-process-a-sequence-of-files

https://www.mathworks.com/matlabcentral/answers/714513-read-image-using-imread-based-on-the-number-of-loop

https://www.mathworks.com/matlabcentral/answers/57300-how-to-read-display-multiple-images-from-a-folder

https://www.mathworks.com/matlabcentral/answers/120073-how-to-read-multiple-jpg-images-in-a-loop

https://www.mathworks.com/matlabcentral/answers/7342-reading-multiple-images-in-a-folder-imread

Answer 1

[VBBV]

image_test{t}=imread([path,'nan_rows' num2str(t)])

[VBBV]

Use a cell array to store images. While concatenation of path with filenames, you need to use num2str

[Yunwei]

Hi,

sorry to say it but the script you posted is not really working,

It causes a error massage saying "File "Z:\collect_data\nan_rows1" does not exist."

I need to get the data array of "nan_rows".

[VBBV]

Is nan_rows a file or folder ? If it's file then it needs additional string called file extension. E.g

image_test{t}=imread([path,'nan_rows', num2str(t),'.jpg'])

Also, check whether the file exists in the folder collect_data

[VBBV]

If nan_rows is folder, then you need to concatenate filename also to the path. Can you share the path and/or files ?

[Yunwei]

nan_row is an array.

I have attached it here.

[DGM]

According to the question, the filenames are in a string array, so I don't know why we're generating number suffixes at all. If we are to generate number suffixes, then we'd actually need to know how they're formatted.

% you have your base path
fprefix = fullfile(matlabroot,'toolbox','images','imdata');

% and you say you have a string array of filenames
fnames = ["cameraman.tif" "tire.tif" "coins.png" "strawberries.jpg"];

nfiles = numel(fnames);
image_test = cell(nfiles,1); % preallocate
for k = 1:nfiles
    image_test{k} = imread(fullfile(fprefix,fnames(k)));
end

montage(image_test)

Build the path with fullfile(). If you have to programmatically construct the filename, using sprintf() is simpler and more readable imo.

[Yunwei]

That's exactly what l need.

Thank you so much for your help!