well, you can use the GEGL operations in gimp fairly easily.
in both the color menu and view menu, select use GEGL. Then in the Tools menu, you can select GEGL operation and a box pops up to let you select what you wish to do.
but working with raw images, do you have the ufraw-gimp package installed? It's a gimp plugin that lets you pull raw images from the camera and work with them.
yum install ufraw-gimp