[R] how to standardize raster image (GeoTiff) in R?

[Angela Smith]

Hi R user, 
Would you give me some hints on to standardize the raster image (GeoTiff). I used the following code but did not work. would you give me some hints on it?

#----------------------------------
#code
# center with 'apply()'
center_apply <- function(x) {
    apply(x, 2, function(y) y - mean(y))
}
# import data
im1<-("image1.tif")
im2<-("image2.tif")
image<-stack(im1,im2)

# standardize (a mean of zero and unit variance) of the rasetr images 
st<-center_apply(image)

but it did not work. any suggestions?




 		 	   		  
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