https://github.com/imdrasil/crymagick
CryMagick is a ImageMagick command line interface for crystal. Inspired by minimagick.
image = CryMagick::Image.open("input.jpg")
image.path #=> "/var/folders/k7/6zx6dx6x7ys3rv3srh0nyfj00000gn/T/magick20140921-75881-1yho3zc.jpg"
image.resize "100x100"
image.format "png"
image.write "output.png"