R plot raster with real colors

I'have a raster image from Scran25 IGN. In Qgis, it opens perfectly but in R (with rgdal or raster packages), I do not know how to keep the original colors like this exemple?

I have tried

library('rgdal')

library('raster')

scan25<-readGDAL("./Banyuls/MyCreate/etudehydoAOC/etudehydoAOC/Scan25/vrt_4communes.vrt")
communes<-readOGR(dsn = "./Banyuls//MyCreate/Surface_4communes/",layer = "4communesAOC")

scan25<-raster(scan25)
test<-aggregate(scan25,10,mean)

plot(communes)
plot(test,add=T)

And the result is