Supplying a total input events/point source/second is the preferred activation input. This is converted to input events/point source/CCD frame according to the frame time in ModeParams. The input PSFimage is normalised to unity, and from this the localised pixel-by-pixel count rate per frame is established.
The calculation depends on the pattern types selected, with progressively more complex arithmetic for the larger patterns (see J Ballet Ast Ap Suppl Ser v 135 pp371-381).
The output intensity () in each case is modelled as follows, where
is the input intensity per pixel :
and the are the fractional pattern occurrences taken from the pattern library CCF, but corresponds to patterns 1,2,3 and 4 , corresponds to patterns 5,6,7 and 8 and corresponds to patterns 9,10,11 and 12.