'**SUMMARY**
Get Background of the Image. For more info read
http://opencvpython.blogspot.in/2012/07/background-extraction-using-running.html
**PARAMETERS**
No Parameters
**RETURNS**
Image - SimpleCV.ImageClass.Image
**EXAMPLE**
>>> while (some_condition):
... img1 = cam.getImage()
... ts = img1.track("camshift", ts1, img, bb)
... img = img1
>>> ts.getBackground().show()'

def getBackground(self):

    imgs = self.trackImages(cv2_numpy=True)
    f = imgs[0]
    avg = np.float32(f)
    for img in imgs[1:]:
        f = img
        cv2.accumulateWeighted(f, avg, 0.01)
        res = cv2.convertScaleAbs(avg)
    return Image(res, cv2image=True)
