imageEdges.py

def resize(img, height=800):
    """ Resize image to given height """
    rat = height / img.shape[0]
    return cv2.resize(img, (int(rat * img.shape[1]), height))

# Resize and convert to grayscale
img = cv2.cvtColor(resize(image), cv2.COLOR_BGR2GRAY)

# Bilateral filter preserv edges
img = cv2.bilateralFilter(img, 9, 75, 75)

# Create black and white image based on adaptive threshold
img = cv2.adaptiveThreshold(img, 255, cv2.ADAPTIVE_THRESH_GAUSSIAN_C, cv2.THRESH_BINARY, 115, 4)

# Median filter clears small details
img = cv2.medianBlur(img, 11)

# Add black border in case that page is touching an image border
img = cv2.copyMakeBorder(img, 5, 5, 5, 5, cv2.BORDER_CONSTANT, value=[0, 0, 0])

edges = cv2.Canny(img, 200, 250)