From help-octave-request at bevo dot che dot wisc dot edu  Sat Dec 23 17:56:41 2000
Subject: printing from octave; loading images
From: Steve Mann <mann at eecg dot toronto dot edu>
To: help-octave at bevo dot che dot wisc dot edu
Cc: mann at eecg dot toronto dot edu
Date: 	Sat, 23 Dec 2000 18:56:31 -0500

I noticed that imread doesn't work right unless the image is a bmp,
so I wrote the following file "loadpnm.m" that might be of use to
others.  Please consider this GPL Version 2, if a "license" is needed
to distribute or use it.

I left in some lines (commented out) showing how I arrived at the
current embodiment.

Also, I noticed that there is no "print" or "gpp" command to print
the whatever figure is on the screen.

Although I could do a screen grab of the plot, it would be nicer
to have a Matlab-like "print" or "gpp" command to make a PostScript file
of a graph appearing on the screen, rather than using a poor resolution
bitmap screen capture.

Is there a print command in octave yet, or should I write that as well?

% loadpnm.m is based on an earlier cmex program I wrote for Matlab before
% it was able to deal with images -- mann at eecg dot toronto dot edu
% this crude implementation (quick hack) DOESNT PROPERLY HANDLE COMMENTS
% feel free to add that feature (fscanf past "#" signs up to "\n")
function [R G B]=loadpnm(filename)
[fp err]=fopen(filename,"r");
magicnumber=fscanf(fp, "P%d",1); %
[imagesize]=fscanf(fp, "%d %d",2); % must pass number of arguments wanted or
                                   % keeps reading and may read into image if
                                   % pixel values are in range of ascii numbers

%carriagereturnisagarbagebyte=fscanf(fp, "\n",1);
%imagedepth=fscanf(fp, "%d\n",1);
imagedepth=fscanf(fp, "%d",1);
newlinegarbage=fread(fp,1,"uchar");

M=imagesize(2); N=imagesize(1); % reversed convention
fprintf(stderr,"loadpnm: magic=%d;  M=%d, N=%d;  depth=%d\n",magicnumber,M,N,imagedepth);

if magicnumber == 5 % reading a pgm
  if nargout~=1
    error("magic number of a single output argument must now be P5; P7, P9, etc. not yet supported")
  end%if
%%  [r mycount]=fread(fp,M*N,"uchar");
%  R=reshape(r,M,N);
%%  R=reshape(r,N,M).';
%  [R mycount]=fread(fp,[M N],"uchar");
%  [R mycount]=fread(fp,[N M],"uchar").';% can't transpose list
  R=fread(fp,[N M],"uchar").'; % must not read mycount!!!
end%if
if magicnumber == 6 % reading a ppm
  if nargout~=3
    error("magic number of a single output argument must now be P5; P7, P9, etc. not yet supported")
  end%if
  [rgb mycountrgb]=fread(fp,3*M*N,"uchar");
  RGB=reshape(rgb,3,M*N);
  R=reshape(RGB(1,:),N,M).';
  G=reshape(RGB(2,:),N,M).';
  B=reshape(RGB(3,:),N,M).';
end%if

fclose(fp);



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