def derivative(self):
        temp = np.array(self,dtype='float32')
        d = [0]
        d += list(temp[1:]-temp[0:-1])
        retVal = LineScan(d,image=self.image,pointLoc=self.pointLoc,pt1=self.pt1,pt2=self.pt2)
        #retVal.image = self.image
        #retVal.pointLoc = self.pointLoc
        return retVal
**SUMMARY**
dataset/ETHPy150Open sightmachine/SimpleCV/SimpleCV/LineScan.py/LineScan.derivative