new_contents: """
  this function calculates that percent of time a fish spends on the white side of a black/white tank
  
  started 13 August 2015, luke reding
  """
  
  import cv2, sys, csv
  import numpy as np
  
  # read video file
  
  # in a loop, query frames
  
  # use same function as in normal tracking code to get photo of empty tank
  
  # for each frame, do blurring followed by background subtraction, thresholding at some level TBD
  
  # order the contours by length and take the longest one
  
  # write it to a csv file
  
  # done
  
subject: Create scototaxisTracking.py