ImageMagick and GD are 2 of the most widespread graphic software libraries on the market. They make the dynamic creation and editing of images and graphs on a website doable, so they should be installed on a server if you host your websites on it and you would like to have something different from static images with fixed dimensions. If ImageMagick and GD are installed, you shall be able to edit any image in various ways - create thumbnails, change the colors, flip it, blur it, etc. Of course, these adjustments are feasible if the script app that you use on your site enables you to carry out such things. The two libraries can be used with a lot of website development languages - PHP, Python, Perl, etcetera., and support more than one hundred commonly used image formats that you will be able to work with - PNG, PSD, JPEG, TIFF, GIF and many others.