Changing all images in a specific folder to type jpeg in matlab

Question

I need to change (and not to keep the old) all the images in a specific folder (and subfolders) to format of type jpeg and save all of the images in one folder. I'm new to Matlab. What I tried:

function convertImages(Folder,ImgType)
Imgs = dir(fullfile(Folder,ImgType));
for i=1:numel(Imgs)
    oldFilename = fullfile(Folder, Imgs(i).name);
    [~,name,~] = fileparts(Imgs(i).name);
    newFilename = fullfile(Folder, strcat(name, '.jpg'));
    imwrite(imread(oldFilename), newFilename);
end
end

When I try to run convertImages('images','png'), Imgs is empty - but I have in the folder 6 files and two of them are png.

When I try to run convertImages('images','*') Imgs loads 8 files, two of them are '.' and '..' , two files I cannot see and it crashes matlab.

Any help will be appreciated!

Answer 1

First, the '.' and '..' stand for the current and parent directories.
Now in order to support multiple types what I would do is make ImgType a cell array with all possible types. For example:

ImgType = {'.png','gif'};

and use

Imgs = dir(fullfile(Folder,'*')); 

In order to avoid the first 2 entries of Imgs just start the loop from 3 instead of 1. Finally in order to check the file type you can do:

[~,name,ext] = fileparts(Imgs(i).name);
if any(cellfun(@(x) strcmp(x,ext), ImgType))
...
end