HOWTO: Tile multiple images together with ImageMagick
1) Tile images in a grid
montage -mode concatenate -tile 2x2 <inputfile>.jpg <outputfile>.jpg
2) Tile images with spacing and a border
montage -geometry 1040x1040+10+10 -bordercolor white yankee-1.jpg yankee-2.jpg yankee-4.jpg yankee-3.jpg yankee.jpg
http://superuser.com/questions/290656/combine-multiple-images-using-imagemagick https://www.thekoikeepers.com/ImageMagick-5.5.7/www/montage.html