Here's a program I like to crop and change to aspect ratio of a folder (batch) of photos. It's very easy to use and includes a TV safe area graphic for use in video.
"The purpose of this program is to make it easy to crop a batch of images to a specific aspect ratio. The black border area may be included if necessary, and the colour of the border changed. The Safe Area can be shown so you can make sure none of your image will be lost off the edge of a normal TV screen. There's a batch mode with each picture presented to you in turn. All you have to do is decide where to crop and hit Save."