Read/Write Portable Anymap Images
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 (general
|
... |
further arguments passed to |
object |
an object of class |
forceplain |
logical; if true, an ASCII pnm file is written. Default is to write a binary (raw) file. |
type |
one of |
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).
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)
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