( sorry if this is a duplicate, I am not sure if hotmail is dropping some of my posts. Thanks )
> You obviously want to delegate inner loops to R packages that execute as native, hopefully optimized, code. Generally a google search that starts with "R CRAN" will help. In this case it looks like a few packages available, > http://www.google.com/search?sclient=psy&hl=en&q=R+cran+median+filter > > > > > > > > > > > > > > ---------------------------------------- >> Date: Sun, 27 Mar 2011 07:56:11 -0700 >> From: chuan...@hotmail.com >> To: r-help@r-project.org >> Subject: [R] Asking Favor For the Script of Median Filter >> >> Hello,everybody. My name is Chuan Zun Liang. I come from Malaysia. I am just >> a beginner for R. Kindly to ask favor about median filter. The problem I >> facing as below: >> >> >>> x<-matrix(sample(1:30,25),5,5) >>> x >> [,1] [,2] [,3] [,4] [,5] >> [1,] 7 8 30 29 13 >> [2,] 4 6 12 5 9 >> [3,] 25 3 22 14 24 >> [4,] 2 15 26 23 19 >> [5,] 28 18 10 11 20 >> >> This is example original matrices of an image. I want apply with median >> filter with window size 3X# to remove salt and pepper noise in my matric. >> Here are the script I attend to writing.The script and output shown as >> below: >> >>> MedFilter<-function(mat,sz) >> + {out<-matrix(0,nrow(mat),ncol(mat)) >> + for(p in 1:(nrow(mat)-(sz-1))) >> + {for(q in 1:(ncol(mat)-(sz-1))) >> + {outrow<-median(as.vector(mat[p:(p+(sz-1)),q:(q+(sz-1))])) >> + out[(p+p+(sz-1))/2,(q+q+(sz-1))/2]<-outrow}} >> + out} >> >>> MedFilter(x,3) >> [,1] [,2] [,3] [,4] [,5] >> [1,] 0 0 0 0 0 >> [2,] 0 8 12 14 0 >> [3,] 0 12 14 19 0 >> [4,] 0 18 15 20 0 >> [5,] 0 0 0 0 0 >> >> Example to getting value 8 and 12 as below: >> >> 7 8 30 8 30 29 >> 4 6 12 (median=8) 6 12 5 (median=12) >> 25 3 22 3 22 14 >> >> Even the script can give output. However, it is too slow. My image size is >> 364*364. It is time consumption. Is it get other ways to improving it? >> >> Best Wishes >> Chuan ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.