pnm
From pixmap v0.4-11
by Friedrich Leisch
Read/Write Portable Anymap Images
Reading and writing of bitmap images in PBM (black/white), PGM (grey) and PPM (color) format.
Usage
read.pnm(file, ...)
write.pnm(object, file= NULL, forceplain = FALSE, type = NULL, maxval = 255)
Arguments
- file
- name of the pnm file (general
connections
do not work at the moment). - ...
- further arguments passed to
pixmap
(likebbox
). - 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.
See Also
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)
Community examples
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