Before April 2001, the top 20-30 pixels of the ISAAC image were vignetted. This vignetting was removed during the March 2001 intervention. So, for data taken before April 2001, this region can be trimmed without any loss of information.
There are a lot of bad pixels on the right hand edge of the array. Users may want to trim the 10 last columns of the ISAAC image or alternatively flag them as bad.
The jitter command can replace bad pixels by an average of their valid neighbors. It cannot trim whole regions.