  We describe the most general homogenous, planar, light-ray-direction-changing
sheet that performs one-to-one imaging between object space and image space.
This is a non-trivial special case (of the sheet being homogenous) of an
earlier result [J. Courtial, Opt. Commun.282, 2480 (2009)]. Such a sheet can be
realised, approximately, with generalised confocal lenslet arrays.
