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

@classmethod
def from_stream(cls, stream):

    stream_rdr = StreamReader(stream, LITTLE_ENDIAN)
    px_width = stream_rdr.read_long(18)
    px_height = stream_rdr.read_long(22)
    horz_px_per_meter = stream_rdr.read_long(38)
    vert_px_per_meter = stream_rdr.read_long(42)
    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)
