Center-to-limb variation of the amount of penumbral 3LPs (left) and RPPs (right). Results for Fe I 630.25 nm and Fe I 1566.2 nm are depicted in the top and bottom panels respectively. Each symbol represents a particular sunspot, followed during its disk passage. To extrapolate the values to disk center, we fit a third-order polynomial to the data points of 3LPs (solid black) and a straight line to the RPPs (dashed black).