pamtooctaveimg (1) - Linux Manuals

pamtooctaveimg: convert a Netpbm image to a GNU Octave image

" "netpbm documentation"


pamtooctaveimg - convert a Netpbm image to a GNU Octave image


pamtooctaveimg [netpbmfile]


This program is part of Netpbm(1)

pamtooctaveimg reads a Netpbm image as input and produces a GNU Octave image file as output.

An Octave image file (called 'Octave's image format' in Octave documentation) is a particular kind of Octave data file. It describes two matrices:

the image itself as a list of indexes into a colormap, and
the corresponding colormap as a list of {red, green, blue} triplets.

An Octave data file is an ASCII text file that you use to import data to Octave.

See the
 Image Processing chapter of the GNU Octave manual for details.

pamtooctaveimg writes the output Octave image to Standard Output.


netpbmfile is the name of the file containing the input PNM or PAM image, or - to indicate Standard Input. If you don't specify netpbmfile, the input is from Standard Input. pamtooctaveimg converts only the first image in the input stream.


   % pamtooctaveimg myimage.ppm > myimage.img
   % octave
   > [img,map] = loadimage("myimage.img");

   # (At this point, img is an X by Y matrix and map is a 3 by M matrix.)

   > imshow(img,map);   # Displays img with colormap map
   > [r,g,b] = ind2rgb(img,map);

   # (r, g, and b are now each X by Y matrices of color levels [0 to 1].)

   > [newimg,newmap] = rgb2ind(r,b,g);   # Swap the blue and green channels.
   > saveimage("newimage.ppm", newimg, "ppm", newmap);  # Save as a PPM file.


There is no octavetopam program. However, GNU Octave's saveimage command can save images in PPM format.


pamtooctaveimg was new in Netpbm 10.39 (June 2007).


Copyright (C) 2007 Scott Pakin, scott+pbm [at]


octave(1) , pam(1)