That depends on what do you mean by the database of the images. See imageDatastore: https://www.mathworks.com/help/releases/R2020a/matlab/ref/matlab.io.datastore.imagedatastore.html, but that is not equivalent to creating a .mat file for images.
You can load all the images and save them in a cell array. The cell array can then be stored in .mat file.
files = dir('*.jpg'); % read all jpg images in current folder
images = cell(1,numel(files));
for i=1:numel(files)
images{i} = imread(fullfile(files(i).folder, files(i).name)); % load images in the cell array
end
save('images.mat', 'images');
