import cv2
import numpy as np


def preprocess_image(img):

    if len(img.shape) == 3:
        gray = cv2.cvtColor(img, cv2.COLOR_RGB2GRAY)
    else:
        gray = img.copy()

    gray = cv2.GaussianBlur(gray, (3, 3), 0)

    _, binary = cv2.threshold(
        gray,
        180,
        255,
        cv2.THRESH_BINARY_INV
    )

    kernel = np.ones((2, 2), np.uint8)

    binary = cv2.morphologyEx(
        binary,
        cv2.MORPH_CLOSE,
        kernel
    )

    return binary


def remove_noise(binary):

    kernel = np.ones((2, 2), np.uint8)

    cleaned = cv2.morphologyEx(
        binary,
        cv2.MORPH_OPEN,
        kernel
    )

    return cleaned