A video coding and decoding method, wherein a picture is first divided
into sub-pictures corresponding to one or more subjectively important
picture regions and to a background region sub-picture, which remains
after the other sub-pictures are removed from the picture. The
sub-pictures are formed to conform to predetermined allowable groups of
video coding macroblocks (MBs). The allowable groups of MBs can be, for
example, of rectangular shape. The picture is then divided into slices so
that each sub-picture is encoded independent of other sub-pictures except
for the background region sub-picture, which may be coded using another
sub-pictures. The slices of the background sub-picture are formed in a
scan-order with skipping over MBs that belong to another sub-picture. The
background sub-picture is only decoded if all the positions and sizes of
all other sub-pictures can be reconstructed on decoding the picture.