dev2bitmap {grDevices} | R Documentation |
Graphics Device for Bitmap Files via Ghostscript
Description
bitmap
generates a graphics file.
dev2bitmap
copies the current graphics device to a file in a
graphics format.
Usage
bitmap(file, type = "png16m", height = 7, width = 7, res = 72,
units = "in", pointsize, taa = NA, gaa = NA, ...)
dev2bitmap(file, type = "png16m", height = 7, width = 7, res = 72,
units = "in", pointsize, ...,
method = c("postscript", "pdf"), taa = NA, gaa = NA)
Arguments
file |
The output file name, with an appropriate extension. |
type |
The type of bitmap. |
width , height |
Dimensions of the display region. |
res |
Resolution, in dots per inch. |
units |
The units in which |
pointsize |
The pointsize to be used for text: defaults to something reasonable given the width and height |
... |
Other parameters passed to |
method |
Should the plot be done by |
taa , gaa |
Number of bits of antialiasing for text and for graphics respectively. Usually 4 (for best effect) or 2. Not supported on all types. |
Details
dev2bitmap
works by copying the current device to a
postscript
or pdf
device, and
post-processing the output file using ghostscript
.
bitmap
works in the same way using a postscript
device
and post-processing the output as ‘printing’.
You will need ghostscript
: the full path to the executable can
be set by the environment variable R_GSCMD. If this is unset, a
GhostScript executable will be looked for by name on your path: on a
Unix alike "gs"
is used, and on Windows the setting of the
environment variable GSC is used, otherwise commands
"gswi64c.exe"
then "gswin32c.exe"
are tried.
The types available will depend on the version of ghostscript
,
but are likely to include
"jpeg"
, "jpegcmyk"
, "jpeggray"
,
"tiffcrle"
, "tiffg3"
,
"tiffg32d"
, "tiffg4"
, "tiffgray"
, "tifflzw"
,
"tiffpack"
, "tiff12nc"
, "tiff24nc"
, "tiff32nc"
"png16"
, "png16m"
, "png256"
, "png48"
,
"pngmono"
, "pnggray"
, "pngalpha"
,
"bmp16"
, "bmp16m"
"bmp256"
, "bmp32b"
,
"bmpgray"
, "bmpmono"
.
The default type, "png16m"
, supports 24-bit colour and
anti-aliasing. Type "png256"
uses a palette of 256 colours and
could give a more compact representation. Monochrome graphs can use
"pngmono"
, or "pnggray"
if anti-aliasing is desired.
Plots with a transparent background and varying degrees of
transparency should use "pngalpha"
.
Note that for a colour TIFF image you probably want "tiff24nc"
,
which is 8-bit per channel RGB (the most common TIFF format). None of
the listed TIFF types support transparency. "tiff32nc"
uses
8-bit per channel CMYK, which printers might require.
For formats which contain a single image, a file specification like
Rplots%03d.png
can be used: this is interpreted by Ghostscript.
For dev2bitmap
if just one of width
and height
is
specified, the other is chosen to preserve the aspect ratio of the
device being copied. The main reason to prefer method = "pdf"
over the default would be to allow semi-transparent colours to be used.
For graphics parameters such as "cra"
that need to work in
pixels, the default resolution of 72dpi is always used.
On Windows only,
paths for file
and R_GSCMD which contain spaces are
mapped to short names via shortPathName
.
Value
None.
Conventions
This section describes the implementation of the conventions for
graphics devices set out in the ‘R Internals’ manual. These
devices follow the underlying device, so when viewed at the stated
res
:
The default device size is 7 inches square.
Font sizes are in big points.
The default font family is (for the standard Ghostscript setup) URW Nimbus Sans.
Line widths are as a multiple of 1/96 inch, with no minimum.
Circle of any radius are allowed.
Colours are interpreted by the viewing/printing application.
Note
On Windows,
Use of bitmap
will leave a temporary file (with file name
starting Rbit
).
Although using type = "pdfwrite"
will work for simple plots, it
is not recommended. Either use pdf
to produce PDF
directly, or call ps2pdf -dAutoRotatePages=/None
on the
output of postscript
: that command is optimized to do
the conversion to PDF in ways that these functions are not.
See Also
savePlot
, which for windows
and
X11(type = "cairo")
provides a simple way to record a PNG
record of the current plot.
postscript
, pdf
, png
,
jpeg
, tiff
and bmp
.
To display an array of data, see image
.