Return |Bmp| instance having header properties parsed from the BMP
        image in *stream*.

def from_stream(cls, stream):
        """
        Return |Bmp| instance having header properties parsed from the BMP
        image in *stream*.
        """
        stream_rdr = StreamReader(stream, LITTLE_ENDIAN)

        px_width = stream_rdr.read_long(0x12)
        px_height = stream_rdr.read_long(0x16)

        horz_px_per_meter = stream_rdr.read_long(0x26)
        vert_px_per_meter = stream_rdr.read_long(0x2A)

        horz_dpi = cls._dpi(horz_px_per_meter)
        vert_dpi = cls._dpi(vert_px_per_meter)

        return cls(px_width, px_height, horz_dpi, vert_dpi)