See VideoWriter(): https://www.mathworks.com/help/releases/R2020a/matlab/ref/videowriter.html. Something like this will work
imgSet = % create the imageset object
v = VideoWriter('vidFileName.mpr', 'MPEG-4');
open(v)
for i=1:imgSet.Count
frame = read(imgSet,i);
writeVideo(v, frame);
end
close(v)
This assumes that all images have same resolution.
