def remove_repeated_channel(image):
    """Remove repeated channel in grayscale images.
       Opencv read grayscale images into 3-channel if not specified, so sometimes people may output a 3-channel
       grayscale image.

    Parameters
    ----------
    image: array
    Grayscale images with 3 repeated channels

    Returns
    -------
    image: array
    Grayscale images with 1 channel
    """
    return image[:, :, 0]