ImageMagick and GD are 2 of the most popular graphic software libraries available. They make the dynamic creation and editing of images and graphs on a site possible, so they should be installed on a server if you host your websites on it and you would like to have something different than static images with fixed dimensions. If ImageMagick and GD are installed, you shall be able to edit any image in a variety of ways - generate thumbnails, change the colors, flip it, blur it, etcetera. However, these tweaks are feasible if the script application that you employ on your site permits you to perform such things. The 2 libraries can easily be used with various programming languages - PHP, Python, Perl, and so forth., and support more than 100 widely used image formats that you will be able to work with - PNG, PSD, JPEG, TIFF, GIF and many more.