class ImageChange:
...
def isStable(self):
        delta=abs(self.movingAverage.gradient())
        stable=delta<ImageChange.gradientDelta
        if stable:
            self.stableCounter+=1
        else:
            self.stableCounter=0    
        return stable  
...
class SimpleDetector:
def updateState(self,cbImageSet):
        calibrationWindow=5
        
        ic=self.imageChange
        ics=ic.changeState
        if ics==ChangeState.CALIBRATING:
            # leave calibrating when enough stable values are available
            if ic.isStable() and ic.stableCounter>=calibrationWindow:
                ic.changeState=ChangeState.PRE_MOVE
        elif ics==ChangeState.PRE_MOVE:
            if not ic.isStable():
                ic.changeState=ChangeState.IN_MOVE
                ic.minInMove=ic.pixelChanges
                ic.maxInMove=ic.pixelChanges
        elif ics==ChangeState.IN_MOVE:
            ic.maxInMove=max(ic.maxInMove,ic.pixelChanges)
            peak=ic.maxInMove-ic.minInMove
            dist=ic.pixelChanges-ic.minInMove
            if peak>0:
                relativePeak=dist/peak
                if ic.isStable():
                    if relativePeak<0.1:
                        self.onMoveDetected(cbImageSet)