filterim<-function(Im,Masksizeh,Masksizev,Masktype) {
# Use odd dim Masksize
#
# Masksizeh is the horizontal size mask
# Masksizev is the vertical size mask
# Masktype: 0=maxfilter, 1=minfilter, 2=meanfilter, 3=medianfilter
#
m1<-Masksizeh
m2<-Masksizev
n1<-dim(Im)[1]
n2<-dim(Im)[2]
Imu<-matrix(0,n1+2*floor(m1/2),n2+2*floor(m2/2))
Imu[(floor(m1/2)+1):(n1+floor(m1/2)),(floor(m2/2)+1):(n2+floor(m2/2))]<-Im
Imo<-Imu
# mirror edges
for (zz1 in ((floor(m1/2)+1):(n1+floor(m1/2)))) {
 for (zz2 in ((floor(m2/2)+1):(n2+floor(m2/2)))) {
  if (Masktype==0) { 
    Imo[zz1,zz2]<-max(Imu[(zz1-floor(m1/2)):(zz1+floor(m1/2)),(zz2-floor(m2/2)):(zz2+floor(m2/2))]) }
  if (Masktype==1) {
    Imo[zz1,zz2]<-min(Imu[(zz1-floor(m1/2)):(zz1+floor(m1/2)),(zz2-floor(m2/2)):(zz2+floor(m2/2))]) }
  if (Masktype==2) {
   Imo[zz1,zz2]<-mean(Imu[(zz1-floor(m1/2)):(zz1+floor(m1/2)),(zz2-floor(m2/2)):(zz2+floor(m2/2))]) }
   if (Masktype==3) {
   Imo[zz1,zz2]<-median(Imu[(zz1-floor(m1/2)):(zz1+floor(m1/2)),(zz2-floor(m2/2)):(zz2+floor(m2/2))]) }
} }
Imo<-Imo[(floor(m1/2)+1):(n1+floor(m1/2)),(floor(m2/2)+1):(n2+floor(m2/2))]
return(Imo) }