How can I see images from usb_cam ?

edit

Good afternoon.

I have usb_camera installed on my groovy raspbian. I have done : rosparam set usb_cam/pixel_format yuyv and after that I wrote : rosrun usb_cam usb_cam_node

I´m being given :

usb_cam video_device set to [/dev/video0]

       usb_cam io_method set to [mmap]

       usb_cam image_width set to [640]

       usb_cam image_height set to [480]

       usb_cam pixel_format set to [yuyv]

       usb_cam auto_focus set to [0]

      10 frames/sec at 1353855178.185472348

      10 frames/sec at 1353855178.314173063

      9 frames/sec at 1353855178.849589157

      10 frames/sec at 1353855179.782349046

       ...

My rostopic list is the next :

/rosout

/rosout_agg

/usb_cam/camera_info

/usb_cam/image_raw

/usb_cam/image_raw/compressed

/usb_cam/image_raw/compressed/parameter_descriptions

/usb_cam/image_raw/compressedDepth

/usb_cam/image_raw/compressedDepth/parameter_updates

/usb_cam/image_raw/compressedDepth/parameter_descriptions

/usb_cam/image_raw/theora

/usb_cam/image_raw/theora/parameter_descriptions

/usb_cam/image_raw/theora/parameter_updates

What´s the next I have to do to be able to see captured images?

Thanks you so much