code: def init(self):
          
          import subprocess
          import fcntl
          
          width = str(self.image_dimensions[0])
          height = str(self.image_dimensions[1])
          
          comlist = self.executable.split() + [width, height, self.tmpfile] # e.g. "python3", "example_process1.py", etc.
          
          try:
              self.p = subprocess.Popen(comlist, stdout=subprocess.PIPE, stdin=subprocess.PIPE)
          except Exception as e:
              print(self.pre, "Could not open external process.  Failed with '"+str(e)+"'")
              return
          
          self.reset()
docs: Start the process