def red_points(checkx, checky, binary_image, checkpoints):
    """
    A function that allows for better user visualization of the
    registration points.

    Parameters
    ----------
    checkx: int
        x-coordinate of one of the maximum curvature points

    checky: int
        y-coordinate of the one of the maxiumum curvature points

    binary_image: boolean array
        Array that depicts the slice as a boolean array

    checkpoints: array
        An array of zeros the size of the fixed image that will be
        filled with values.

    Returns
    -------
    coor_df: checkpoints
        The input array with areas marked for the registration points.

    """
    binaryx, binaryy = binary_image.shape
    checkpoints[checkx, checky] = 255
    kernel = list(range(1, 50))
    xvalues = list(range(checkx - 50, checkx+50))
    for x in xvalues:
        for distances in kernel:
            checkpoints[x, (checky - distances):(checky+distances), 0:1] = 255
    return checkpoints