Yes, two different processing functions are possible in jevois:
def process(self, inframe, outframe): process an incoming image and create an output image. This function is triggered by the JeVois Engine when connected to a host computer over USB and video capture software like AmCap is running
def processNoUSB(self, inframe): process an incoming image and do not output any image, only serial messages. To trigger this mode, since there is no AmCap to control JeVois, you need to connect to the JeVois console and use the setmapping2 and then streamon commands. Or you can put these commands in initscript.cfg so they get loaded when JeVois starts.
See this tutorial for an example of using processNoUSB():
and also see this:
two sections are relevant here:
Operation with streaming video output
Operation with no video output