% Inputs: folder and file extension
% Will plot all files with the chosen extension in the chosen folder
folder = 'C:\Users\pittsl\Desktop\Matlab\train\cup';
ext = 'png'; %extension, no dot
% Get list of all files
content = dir(folder);
allfiles = {content.name};
isExt = endsWith(allfiles,['.',ext],'IgnoreCase',true); % req. r2016b or later https://www.mathworks.com/help/matlab/ref/endswith.html
files = allfiles(isExt);
% Determine subplot layout
nImages = numel(files);
dimN = ceil(sqrt(nImages));
dimM = ceil(nImages/dimN);
nrows = min(dimN, dimM);
ncols = max(dimN, dimM);
% Plot them
for K = 1:nImages
this_image = imread(fullfile(folder,files{K}));
ax = subplot(nrows,ncols, K);
imshow(this_image, 'Parent', ax);
end
For MATLAB releases prior to R2016b, replace the endsWith function with this,
isExt = ~cellfun('isempty',regexpi(allfiles,['.',ext,'$']));
Alternative
To show thumbnail images of all image files within a folder or images with specified extensions, see showImageThumbnails from the File Exchange. Image tiles will be numbered and a table is returned that defines the path to each tile.
folder = 'C:\Users\pittsl\Desktop\Matlab\train\cup';
ext = '.png'; % include dot
showImageThumbnails(folder, ext)
