Magick++

GraphicsMagick is a robust collection of tools and libraries to read, write, and
manipulate an image in any of the more popular image formats including GIF, JPEG, PNG, PDF,
and Photo CD. With GraphicsMagick you can create GIFs dynamically making it suitable for Web
applications. You can also resize, rotate, sharpen, color reduce, or add special effects to
an image and save your completed work in the same or differing image format.