# negate
$ convert black-white.png -negate white-black.png
# rotate
$ convert upside-down.png -rotate 180 rightside-up.png
# resize
$ convert img.gif -resize 64x64 resized_img.gif
#convert to grayscale
$ convert -type Grayscale color.jpg gray.jpg
# find the differences between two images
$ composite img1.jpg img2.jpg -compose difference diff.jpg
# compare images using a metric (can be mse, psnr and more)
$ compare -verbose -metric mse 1.jpg 2.jpg difference.png
# compose two images together using a mask (stencil)
$ convert -size 512x256 tile:img.jpg tile:img2.jpg mask.jpg -composite result.jpg
