save as .txt file from .jpg directories

hi sir, can I know why it cannot save as text file? here is the script

files = dir('*.jpg');
for k = 1:numel(files)
    input_name = files(k).name;
    [path, name, extension] = fileparts(input_name);
    output_name = fullfile(path, [name '.txt']);
    save(files(k).name,'-ASCII')
end

it gives warning:

 Warning: Attempt to write an unsupported data type to an ASCII file.
          Variable 'structuringElement' not written to file. 
 Warning: Attempt to write an unsupported data type to an ASCII file.
          Variable 'subImage' not written to file.

[EDITED, Jan, code and warnings formatted] Please do this by your own in the future - thanks!

Answer 1

[Jan]

The command save writes all variables of the current workspace to disk, if the variables are not specified. When the ASCII format is used, only a subset of the possible types is possible. E.g. how should a nested struct, which contains cell arrays, whose elements are UINT16 arrays, be written unequivocally in ASCII format?!

Either use the binary format -MAT, or specify the variables, which are written and which have the apropriate type. Read doc save for more details.