PNG output tests in R

pngtests.r

library(ggplot2)
p <- ggplot(mtcars, aes(cyl, mpg)) + geom_point()


# Standard png device, with type="cairo"
# Result: not antialiased
png('png_cairo.png', type="cairo")
p
dev.off()


# Standard png device, with type="cairo-png"
# Result: not antialiased
#   Setting antialias argument to "subpixel" does nothing
png('png_cairo-png.png', type="cairo-png", antialias="subpixel")
p
dev.off()


# Using png with quartz
# Result: antialiased
# Problems: works only on Mac
png('png_quartz.png', type="quartz")
p
dev.off()


# Using cairoPNG from Cairo library.
# Result: antialiased
# Problems: fonts are messed up
library(Cairo)
CairoPNG('CairoPNG.png')
p
dev.off()


# ggsave with Cairo_png from cairoDevice
# Result: antialiased output
# Issues:
#  - requires Cairo library (~56MB download on Mac)
#  - needs to be tested on Windows, Linux
# Problems: Fonts are inconsistent across platforms
library(cairoDevice)
p
ggsave('Cairo_png.png', device=Cairo_png, width=5, height=5, dpi=72)

Great script. I noted exactly the same problems.