session_grid(NULL)
a <- ursa_dummy(nband=1,min=0,max=100)
a[a<30] <- NA
compose_open()
panel_new()
ct <- panel_raster(a)
panel_decor(graticule.col="green4",graticule.lwd=2,scalebar.col="brown")
compose_legend(ct)
compose_close()
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