png {graphics} | R Documentation

## JPEG and PNG graphics devices

### Description

A graphics device for JPEG or PNG format bitmap files.

### Usage

    jpeg(filename = "Rplot%03d.jpeg", width = 480, height = 480,
         pointsize = 12, quality = 75, bg = "white", ...)
    png(filename ="Rplot%03d.png", width = 480, height = 480,
        pointsize = 12, bg = "white", ...)

### Arguments

`filename` | the name of the output file. The page number is substituted if an integer format is included in the character string. (The result must be less than `PATH_MAX` characters long, and may be truncated if not.) Tilde expansion is performed where supported by the platform.
`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.

### Warning

If you plot more than one page on one of these devices and do not include something like `%d` for the sequence number in `file`, the file will contain the last page plotted.

### 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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