@staticmethod
def _get_scale(metadata):
    """
        Returns the size of a pixel and the unit as tuple

        It is assumed that the scale of a pixel in x and y
        is the same. This only works if it is image metadata.
        """
    pixelsize = float(metadata['BinaryResult']['PixelSize']['width'])
    pixelunit = metadata['BinaryResult']['PixelUnitX']
    return pixelsize, pixelunit
