| pnm {pixmap} | R Documentation |
Reading and writing of bitmap images in PBM (black/white), PGM (grey) and PPM (color) format.
read.pnm(file, ...) write.pnm(object, file= NULL, forceplain = FALSE, type = NULL, maxval = 255)
file |
name of the pnm file. |
... |
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. |
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.
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.
Roger Bivand and Friedrich Leisch
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)