pnm: Read/Write Portable Anymap Images

Description

Reading and writing of bitmap images in PBM (black/white), PGM (grey) and PPM (color) format.

Usage

read.pnm(file, ...)
write.pnm(object, file="Rimage.pnm", forceplain=FALSE,
          type=NULL, maxval=255)

Arguments

file

name of the pnm file.

...

Further arguments passed to pixmap (like bbox).

object

an object of class "pixmap".

forceplain

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.

Value

read.pnm returns an object of class pixmapRGB for color pixmaps (ppm), and an object of class pixmapGrey for pbm and pgm.

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.

Examples

Run this code

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)