Left panels: probability density function of Q/I, U/I and V/I in the continuum. Right panels: noise distribution for the line core of Sr I inferred from that observed at the continuum wavelength in the various Stokes parameters (magenta dashed lines). The continuum image is classified into granules and intergranules, for which we plotted the Stokes signals separately. A shifted noise distribution (green dashed line) is shown to match the Sr I line core Stokes Q/I signals in the intergranules.