filter  : 3x3 rotation symmetrical filter.
central:cc, diagonal:cd, hori/verti:chv.
out = filter(in) * (mul/1024) + add
cmd : filter in, out, cd, chv, cc, mul, add
dflt: filter  A,  B , 0 , -1 , 5 ,1024,  0
range:    <A,B><A,B>,<-/+1000>,<10000><-+255>
