jcResizerCmd is a command line tool to that lets you resize images in bulk. This tool is also capable of watermarking an Image with either Text, Image or both in bulk.
A quick example command for jcResizerCmd.exe look like this
-wm-text="copyright jaspreetchahal.org 2012"
This util is less than 25Kb in size and does what it is designed to do. You can read more about options from documentation page. Rest assured that works with most of the camera pictures. You can also use this tool to convert from one image format to another. e.g. jpg to png OR jpg to ico
Many examples are provided on Usage page so go ahead and check them out.