'Filename from which this image part was originally created. A generic
name, e.g. \'image.png\', is substituted if no name is available, for
example when the image was loaded from an unnamed stream. In that
case a default extension is applied based on the detected MIME type
of the image.'

@property
def filename(self):

    if (self._image is not None):
        return self._image.filename
    return (u'image.%s' % self.partname.ext)
