name of the pnm file (general
connections do not work at the moment).
...
further arguments passed to pixmap (like
bbox).
object
an object of class "pixmap".
forceplain
logical; if true, an ASCII pnm file is written.
Default is to write a binary (raw) file.
type
one of "pbm", "pgm" or "ppm". Default
is to use "pgm" for grey images and "ppm" for color
images.
maxval
the maximum color-component value; the default is a
colour depth of 8 bits, i.e., the integer 255.
Details
read.pnm reads a pnm file and loads the image into an
object of class pixmap.
write.pnm writes an object of class pixmap to a
pnm file, the type argument controls wheter the written image
file is a black-and-white bitmap (pbm), grey (pgm) or color (ppm).
plot.pnm plots a pnm object using the command
image. The only difference is that the element [1,1] of
pnmobj is plotted as the upper left corner (plain
image would plot [1,1] as the lower left corner.
Value
read.pnm returns an object of class pixmapRGB for color
pixmaps (ppm), and an object of class pixmapGrey for pbm
and pgm. Note that the type of file as determined by the first
two bytes according to pnm standards is important, not the
extension of the file. In fact, the file name extension is
completely ignored.
Author(s)
Roger Bivand and Friedrich Leisch
See Also
pixmap
Examples
x <- read.pnm(system.file("pictures/logo.ppm", package="pixmap")[1])
plot(x)
print(x)
x <- read.pnm(system.file("pictures/logo.pgm", package="pixmap")[1])
plot(x)
x <- read.pnm(system.file("pictures/logo.pbm", package="pixmap")[1])
plot(x)