Left panel: sample of a single intensity frame ( component of the K channel), the continuous line represents the location to calculate the intensity profiles; central panel: the observed intensity profile (continuous blue line) and the fitted CLV (continuous green line) along the line reported in the left panel; right panel: the ratio between the observed intensity values of the image and the calculated CLV. The abscissas of the plots reported in the central and right panels are in pixels. The profile range (displayed by dashed line in the central panel) is 810 pixels, corresponding to 90% of the solar disc.