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Message-ID: <loom.20110215T141928-342@post.gmane.org>
Date: 2011-02-15T13:20:59Z
From: Ben Bolker
Subject: readPNG gives warnings and doesn't execute sample code	from help files

Joris Meys <jorismeys <at> gmail.com> writes:

> 
> I believed the standard plotting device on R in 2.12.1 would support
> per-pixel alpha. It does support alpha, as
> 
>  plot(1:2,type="l")
>  polygon(c(1,1,2,2),c(1,2,2,1),col=rgb(60,100,60,60,maxColorValue=255))
> 
> plots correctly. Which device should I use then?

See 

http://developer.r-project.org/Raster/raster-RFC.html

(near the bottom of the page, where it explains that the
Windows device supports alpha but not per-pixel alpha ...)

 cheers
    Ben Bolker