png {base} | R Documentation |
A graphics device for BMP, JPEG or PNG format bitmap files.
bmp(filename="Rplot.bmp", width=480, height=480, pointsize=12) jpeg(filename="Rplot.jpg", width=480, height=480, pointsize=12, quality=75) png(filename="Rplot.png", width=480, height=480, pointsize=12)
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. |
quality |
the `quality' of the JPEG image, as a percentage. Smaller values will give more compression but also more degradation of the image. |
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.
A plot device is opened: nothing is returned to the R interpreter.
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.
Guido Masarotto
## copy current plot to a (large) PNG file dev.print(png, file="myplot.png", width=1024, height=768)