Removing the background of an image - python

Question

I’m developing a code to remove the background of an image, I’m trying to use the Canny border detector to elaborate a mask and try to remove a piece of pipe from the image:

The code I’m working on is this:

img = imread('Imagem.jpg')
gray = cvtColor(img,COLOR_BGR2GRAY)

edges = Canny(gray,10,100) #Utiliza o metodo Canny
edges = dilate(edges, None) # Dilata as linhas da fronteira
edges = erode(edges, None) # remove pequenos "buracos"

contour_info = []
contours, _ = findContours(edges, RETR_LIST, CHAIN_APPROX_NONE)
for c in contours:
    contour_info.append((c, isContourConvex(c),contourArea(c), ))
contour_info = sorted(contour_info, key=lambda c: c[2], reverse=True) 
max_contour = contour_info[0]

mask = np.zeros(edges.shape)
fillConvexPoly(mask, max_contour[0], (255))

mask_stack = np.dstack([mask]*3)    # Cria uma mascara de 3 canais

mask_stack  = mask_stack.astype('float32') / 255.0           
img = img.astype('float32') / 255.0
Mscor = (1.0,1.0,1.0) # Formato BGR                 

masked = (mask_stack * img) + ((1-mask_stack) * Mscor) 
masked = (masked * 255).astype('uint8')

being the result:

I tried to adjust the gradients of the function cv2.Canny, but only gets worse, someone could help me?