Intensity histograms. Left panel: histograms of the bolometric intensity. The bins are logarithmically equidistant with a bin size of 0.01 dex. Middle and right panels: histograms of the normalised intensity fluctuation Î (see Eq. (1)). The bins are linearly equidistant with a bin size of 0.1. Solid curves show the histograms of the entire area, dotted and dashed curves show the histograms of granules and intergranular lanes, respectively, as detected by the algorithm described in Sect. 3.1.