rosed for read-only files

edit

I'm a newbie- and I was trying to use the "rosed" command to edit one of the .cpp source files that came in the package image_view.

However when I follow the instructions here: http://www.ros.org/wiki/ROS/Tutorials/UsingRosEd

after I make the change I cant save it-- it says: "/opt/ros/electric/stacks/image_pipeline/image_view/src/nodes/extract_images.cpp" E212: Can't open file for writing

How do I change the permissions? Obviously "sudo" won't help.

Any help is highly appreciated.