png {base}

R Documentation

JPEG and PNG graphics devices

Description

A graphics device for JPEG or PNG format bitmap files.

Usage

jpeg(filename = "Rplot.jpeg", width = 480, height = 480,
     pointsize = 12, quality = 75, bg = "white", ...)
png(filename ="Rplot.png", width = 480, height = 480,
    pointsize = 12, bg = "white", ...)

Arguments

filename	the name of the output file.
width	the width of the device in pixels.
height	the height of the device in pixels.
pointsize	the default pointsize of plotted text.
quality	the ‘quality’ of the JPEG image, as a percentage. Smaller values will give more compression but also more degradation of the image.
bg	default background colour.
...	additional arguments to the X11 device.

Details

Plots in PNG and JPEG format can easily be converted to many other bitmap formats, and both can be displayed in most modern web browsers. The PNG format is lossless and is best for line diagrams and blocks of solid colour. The JPEG format is lossy, but may be useful for image plots, for example.

png supports transparent backgrounds: use bg = "transparent". Not all PNG viewers render files with transparency correctly. When transparency is in use a very light grey is used as the background and so will appear as transparent if used in the plot. This allows opaque white to be used, as on the example.

R can be compiled without support for either or both of these devices: this will be reported if you attempt to use them on a system where they are not supported. They will not be available if R has been started with --gui=none (and will give a different error message), and they may not be usable unless the X11 display is available to the owner of the R process.

Value

A plot device is opened: nothing is returned to the R interpreter.

Note

These are based on the X11 device, so the additional arguments to that device work, but are rarely appropriate. The colour handling will be that of the X11 device in use.

Author(s)

Guido Masarotto and Brian Ripley

See Also

Devices, dev.print

capabilities to see if these devices are supported by this build of R.

bitmap provides an alternative way to generate PNG and JPEG plots that does not depend on accessing the X11 display but does depend on having GhostScript installed.

Examples

## these examples will work only if the devices are available
## and the X11 display is available.

## copy current plot to a PNG file
## Not run: dev.print(png, file="myplot.png", width=480, height=480)

png(file="myplot.png", bg="transparent")
plot(1:10)
rect(1, 5, 3, 7, col="white")
dev.off()

jpeg(file="myplot.jpeg")
example(rect)
dev.off()

## End(Not run)

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