graphicsmagick.org

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 WebP. 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.