def get_ext_info(hdu):
    """
    Returns name, type and size of a specified HDU extension

    :param hdu: a single extension of a multiextension HDU item
    :type hdu: astropy.io.fits.hdu.image class
    :return: 3- element dictionary with text values for extension name, extension type, and extension size.
    """
    outDict={}
    outDict["name"]=hdu.name
    outDict["type"] = str(hdu).split(" object")[0].split(".")[-1]
    if ((outDict["type"] == 'ImageHDU') and (hdu.shape)):
        outDict["size"] = "{} x {}".format(hdu.shape[0],hdu.shape[1])
    elif "table" in outDict["type"].lower():
        nRows = len(hdu.data)
        nCols = len(hdu.data[0])
        outDict["size"] = "{}R x {}C".format(nRows,nCols)
    else:
        outDict["size"] = "()"
    return(outDict)