如何填充接触图像边界的轮廓？

Question

I have images which I draw contours on from a brightness threshold, the contours are filled after this from the inside. The issue I have ran in to is filling the contours which are hitting the borders.

The latest attempt was to add borders around the image and removing them after contour fill, yet it does not work with all the files.

Example of the issue displayed [1]: https://imgur.com/a/XyOj0zC

I am open to new approaches to the problem, thank you in advance.

    #open the image as a numpy array, in grayscale
    img_input = cv2.imread(input_folder + "\\" + filename, cv2.IMREAD_GRAYSCALE)

    #blur for more accurate contour detection
    img_blurred = cv2.GaussianBlur(img_input, (5,5), cv2.BORDER_DEFAULT)

    #contour selection with otsu's threshold
    image = cv2.threshold(img_blurred, 0, 255, cv2.THRESH_BINARY + cv2.THRESH_OTSU)[1]

    #border creation to fill border hitting contours
    row, col = image.shape[:2]
    bottom = image[row - 2:row, 0:col]
    mean = cv2.mean(bottom)[0]
    bordersize = 10
    image = cv2.copyMakeBorder(
        image,
        top=bordersize,
        bottom=bordersize,
        left=bordersize,
        right=bordersize,
        borderType=cv2.BORDER_CONSTANT,
        value=255
        )

    #border hole creation so the whole image doesnt get filled due to continous contour by the borders
    image[100:101,0:10] = [0]

    #filling the contours
    cnts = cv2.findContours(image, cv2.RETR_EXTERNAL, cv2.CHAIN_APPROX_SIMPLE)
    cnts = cnts[0] if len(cnts) == 2 else cnts[1]
    cv2.fillPoly(image, cnts, [255, 255, 255])

    #removing the created borders
    y, x = image.shape
    final_img = image[10:y-10, 10:x-10]

    #saving the file
    cv2.imwrite(output_folder + "\\" + filename[:-4] + ".png", final_img)

Answer 1

image = cv2.copyMakeBorder(
    image,
    top=bordersize,
    bottom=bordersize,
    left=bordersize,
    right=bordersize,
    borderType=cv2.BORDER_CONSTANT,
    value=0
    )

I think value=0 is better than value=255.