In fact my image is not only noise, but a matrix with low noise levels and one
small area with higher values. However due to the noise in data is difficult to
detect the peak. Therefore I need to smooth.
Catalina
"Liaw, Andy" wrote:
>
> If I understood you correctly, what you want to try is set the "span"
> argument in loess() to something fairly small (e.g., 0.1 or 0.05). The
> default (0.75) is probably too large for smoothing images.
>
> I'm not sure what you're expecting to see in your simulated example. You
> simulated pure noise, so you should see (nearly) nothing after the smooth.
>
> Andy
>
> -----Original Message-----
> From: Catalina Mesina [mailto:cmesina@cs.vu.nl]
> Sent: Monday, November 25, 2002 10:54 AM
> To: S-news list
> Subject: [S] Gaussian smoothing
>
> Dear all,
>
> I have tried a 3D smoothing of my data, using "loess", or smooth but I did
> not get the right smoothed image.
> Suppose that my data is a matrix "myim" 50x50 and at each point (x,y) in
> the grid I have an intensity value.
>
> myim<-matrix(rnorm(2500),50,50)
>
> x<-seq(1,50,1)
> y<-seq(1,50,1)
> grid<-expand.grid(x,y)
> myd<-data.frame(grid[,1],grid[,2],as.vector(myim))
> sm.myd<-fitted(loess(myd$X3~myd$X1*myd$X2,data=myd))
> image(matrix(myd$X3,50,50))
>
> Then what I would like to have is a gaussian smoothed image (matrix) of
> myim.
>
> I will appreciate every help answer from you.
>
> Catalina
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