Top: radial intensity in the test transit image, corrected for limb darkening, as a function of distance from the centre of the Venusian disc before (black dotted curves) and after image restoration with the various PSF estimates. a) With K₁ (black solid curve). b) With the PSFs obtained by blurring the edge of the disc of zeroes in the artificial image with kernels representing Gaussian functions with standard deviations of 0.2, 0.3 and 0.4 arcsec (blue dotted, dashed and solid curves). c) With the PSF retrieved by subtracting the estimated aureole intensity from the mean transit image (green solid curve). d) With K₂ (red solid curve). Middle and bottom: blow-up insets of the boxed areas. The radius of the Venusian disc, a free parameter in the LMA optimization, is in all instances about 29.3 arcsec and not marked to avoid cluttering. The horizontal dashed lines follow unit intensity. The test transit image was corrected for limb darkening by normalizing it by the surface fit, computed as done for the mean transit image in Sect. 2.2.