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import cv2 

lowT = 100
maxT = 200

def CannyThreshold(i):
    global lowT 
    lowT = i

def onMouse( event, x, y, flags, param): 
    global lowT
    if event == cv2.EVENT_LBUTTONUP:
        #lowT = x
        pass
    
cameraCapture = cv2.VideoCapture(0) 
cv2.namedWindow('MyWindow') 
cv2.createTrackbar( "Min Threshold:", 'MyWindow', lowT, 200, CannyThreshold)
cv2.setMouseCallback('MyWindow', onMouse) 
print 'Showing camera feed. Click window or press any key to stop.' 
success, frame = cameraCapture.read() 
print success
while success and cv2. waitKey( 1) == -1: 
    success, frame = cameraCapture.read()
    gray = cv2.cvtColor( frame, cv2.COLOR_BGR2GRAY)
    can = cv2.Canny (gray, lowT, lowT * 3)
    cv2.imshow('MyWindow', can) 
    
cameraCapture.release()
cv2. destroyWindow('MyWindow')


    

    




Showing camera feed. Click window or press any key to stop.
True

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