@staticmethod
def __check_neighbor_pixel(x, y, color_ignore, pixel_img, dict_pixel_label,
    list_pixel_full):
    """Check directions of current pixel.
        if color of direction different background color and have label
        label of (x, y) = min(directions)
        @return: label of current pixel (int)
        """
    list_direction = [(x - 1, y), (x - 1, y - 1), (x, y - 1), (x + 1, y - 1)]
    pixel_label = []
    for direction in list_direction:
        if (direction in list_pixel_full and pixel_img[direction] !=
            color_ignore and direction in dict_pixel_label and 
            dict_pixel_label[direction] not in pixel_label):
            pixel_label.append(dict_pixel_label[direction])
    return pixel_label
