SW Image Crop
How it works and what it does?
Install the plugin through the Joomla! installer. Go to Extensions -> Plugins. Find Content – Crop and open it for edit. Define the sizes that you are planning to use on your web site. You may add unlimited sizes, but be aware that if these are more than 10, depending on your server, the upload process may go slower than usual. Enter only values in pixels. Do not enter px or any other characters. After defining the sizes that you are going to use, save the plugin and exit the edit screen. Now when uploading images through the Joomla! Media Manager, these are also resized and cropped (in the center) in the dimensions entered by you in the plugin parameters. The cropped images are stored in folders with their size as a name. For example images with size 640x360 are stored in /images/640x360/filename.jpg
This plugin will NOT crop your already uploaded images. It works only for new uploads. You cannot select what part of the image to crop. It is always cropped in the middle. The plugin creates images in the selected (by you) proportions, but the authors are the one to place the right image with the right size on the right place. If you change the predefined sizes, your existing images will not crop in the new sizes.