Upper panels: histogram of PGs average brightness for blue continuum (left) and G band (right). Black dashed line (INW), black solid line (OUT), and gray solid line (STB). Bottom panels: average brightness as a function of position in the penumbra. Circle signs represent INW, diamond signs represent OUT, and star signs represent STB. The bars indicate a scatter of ±1σ. The dark curve represents the mean intensity averaged over the azimuthal direction at each radial bin. Vertical lines represent the boundary of umbra and penumbra and the boundary of penumbra and surrounding granulation, respectively. The intensity here is measured by the intensity of PG relative to quiet Sun intensity.