png {base}

R Documentation

BMP, JPEG and PNG graphics devices

Description

A graphics device for BMP, JPEG or PNG format bitmap files.

Usage

bmp(filename="Rplot.bmp", width=480, height=480, pointsize=12,
    bg="white")
jpeg(filename="Rplot.jpg", 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, intepreted at 72 dpi, so one point is approximately one pixel.
bg	the initial background colour: can be overridden by setting par("bg").
quality	the ‘quality’ of the JPEG image, as a percentage. Smaller values will give more compression but also more degradation of the image.

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. The BMP format is standard on Windows, and supported elsewhere.

png supports transparent backgrounds on 16-bit (‘High Color’) or better screens: use bg="transparent". Not all PNG viewers render files with transparency correctly.

Value

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

Note

These devices effectively plot on a hidden screen and then copy the image to the required format. This means that they have the same colour handling as the actual screen device, and work best if that is set to a 24-bit or 32-bit colour mode.

Author(s)

Guido Masarotto and Brian Ripley

See Also

Devices, dev.print, bitmap

Examples

## copy current plot to a (large) PNG file
## Not run: dev.print(png, file="myplot.png", width=1024, height=768)

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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