This method steps through the top level elements in the container. For every element that is itself a container holding exactly one CogImage16Range and exactly one CogImage16Grey (and possibly some other objects), copy a reference to that range image into the output array of CogImage16Range references. And copy a reference to the grey image into the output array of CogImage16Grey. And copy the associated top level dictionary key string into the output array of string references. The output arrays may be empty. This method ignores top level elements that are not of type CogVisionDataContainer. This method ignores top level elements that contain more than one CogImage16Range or more than one CogImage16Grey.