ImageMagick and GD are 2 of the most widespread graphic software libraries available. They make the dynamic creation and editing of images and graphs on a website possible, so they must be installed on a web server if you host your websites on it and you would want to have something different than static images with fixed dimensions. If ImageMagick and GD are installed, you will be able to edit any image in various ways - create thumbnails, change the colors, flip it, blur it, etcetera. Of course, these adjustments are feasible if the script application which you use on your site permits you to do such things. The 2 libraries can be used with different web development languages - PHP, Python, Perl, etcetera., and support over a hundred popular image formats that you shall be able to work with - PNG, PSD, JPEG, TIFF, GIF and many more.