[R-sig-Geo] transparency in raster images
Barry Rowlingson
b.rowlingson at lancaster.ac.uk
Tue Aug 25 13:55:46 CEST 2009
I've just been hacking image.SpatialGridDataFrame to support
transparency, either via specifying an alpha band or a constant value
of alpha:
image(foo,red=1,green=2,blue=3,alpha="band4",add=TRUE)
image(foo,red=1,green=2,blue=3,alpha=0.5,add=TRUE)
I don't think what I've done works properly with NAs in the data
though. Has anyone else implemented transparency for SGDFs to save me
spending time fixing little awkward bits like that? Roger?
Barry
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