def xieta2colrow(xi, eta, detsize, fill, npixx, npixy):
    """
    Convert detector xi and eta values to image column and row.

    :param xi: One coordinate of the unprojected detector position.

    :type xi: numpy.ndarray

    :param eta: Second coordinate of the unprojected detector position.

    :type eta: numpy.ndarray

    :param fill: Ration of the detector extent to the image extent.

    :type fill: float

    :param npixx: Number of pixels in the x dimension of an image.

    :type npixx: int

    :param nipxy: Number of pixels in the y dimension of an image.

    :type npixy: int

    :returns: tuple -- A tuple containing the image column and row values.
    """

    col = (((xi/36000.)/(detsize/2.)*fill+1.)/2.*npixx)

    row = (((eta/36000.)/(detsize/2.)*fill+1.)/2.*npixy)

    return col, row