Tiles images into a customizable grid. Part of ImageMagick. More information: https://imagemagick.org/script/montage.php.
montage path/to/image1.jpg path/to/image2.jpg ... path/to/montage.jpg
montage path/to/image1.jpg path/to/image2.jpg ... -geometry +0+0 path/to/montage.jpg
montage path/to/image1.jpg path/to/image2.jpg ... -geometry 640x480+0+0 path/to/montage.jpg
montage path/to/image1.jpg path/to/image2.jpg ... -geometry +0+0 -tile 2x3 montage_%d.jpg
montage path/to/image1.jpg path/to/image2.jpg ... -geometry +0+0 -resize 640x480^ -gravity center -crop 640x480+0+0 path/to/montage.jpg