%LOADPPM	Load a PPM image%%	I = loadppm(filename)%	I = loadppm(filename, n)%%	Returns a matrix containing the image loaded from the PPM format%	file filename.  Handles ASCII (P3) and binary (P6) PGM file formats.%	Result is returned as a 3 dimensional array where the last index%	is the color plane.%%	If the filename has no extension, and open fails, a '.ppm' will%	be appended.  If the file cannot be opened it returns [].%%	Wildcards are allowed in file names.  If multiple files match%	a 4D image is returned where the last dimension is the number%	of images contained.%%	I = loadpgm%%	Presents a file selection GUI from which the user can pick a file.%	Uses the same path as previous call.%% SEE ALSO:	saveppm loadpgm%%	Copyright (c) Peter Corke, 1999  Machine Vision Toolbox for Matlab% Peter Corke 1994% $Header: /home/autom/pic/cvsroot/image-toolbox/loadppm.m,v 1.4 2005/10/30 03:32:08 pic Exp $% $Log: loadppm.m,v $% Revision 1.4  2005/10/30 03:32:08  pic% Improve PPM parser.%% Revision 1.3  2005/07/03 10:59:28  pic% Minor tidyup to status messages.%% Revision 1.2  2003/09/30 18:49:03  pic% Minor bug in wildcard load.%% Revision 1.1.1.1  2002/05/26 10:50:23  pic% initial import%function I = loadppm(file, nseq)	persistent path	if nargin == 0,		if isempty(path) | (path == 0),			[file,npath] = uigetfile([pwd '/*.ppm'], 'loadpgm');		else			[file,npath] = uigetfile([path '/*.ppm'], 'loadpgm');												end		if file == 0,			return;	% cancel button pushed		else			path = npath;			clear npath;		end		I = loadppm2(file);	else		if isempty(findstr(file, '.ppm'))			file = [file '.ppm'];		end		slashes = findstr(file, '/');		if isempty(slashes),			fpath = './';		else			k = slashes(end);			fpath = file(1:k);		end		s = dir(file);		% do a wildcard lookup		switch length(s),		case 0,			error('cant find specified file');		case 1,			I = loadppm2([fpath s.name]);		otherwise,			if nargin == 1,				for i=1:length(s),					I(:,:,:,i) = loadppm2([fpath s(i).name]);				end			else				I(:,:,:) = loadppm2([fpath s(nseq).name]);			end		end	endfunction RGB = loadppm2(file)	white = [' ' 9 10 13];	% space, tab, lf, cr	white = setstr(white);	fid = fopen(file, 'r');	if fid < 0,		fid = fopen([file '.ppm'], 'r');	end	if fid < 0,		fid = fopen([file '.pnm'], 'r');	end	if fid < 0,		R = [];		disp(['Couldn''t open file' file]);		return	end			magic = fread(fid, 2, 'char');	while 1		c = fread(fid,1,'char');		if c == '#',			fgetl(fid);		elseif ~any(c == white)			fseek(fid, -1, 'cof');	% unputc()			break;		end	end	cols = fscanf(fid, '%d', 1);	while 1		c = fread(fid,1,'char');		if c == '#',			fgetl(fid);		elseif ~any(c == white)			fseek(fid, -1, 'cof');	% unputc()			break;		end	end	rows = fscanf(fid, '%d', 1);	while 1		c = fread(fid,1,'char');		if c == '#',			fgetl(fid);		elseif ~any(c == white)			fseek(fid, -1, 'cof');	% unputc()			break;		end	end	maxval = fscanf(fid, '%d', 1);	c = fread(fid,1,'char');	if magic(1) == 'P',		if magic(2) == '3',			fprintf('%s: binary PPM file (%dx%d)\n', file, cols, rows)			I = fscanf(fid, '%d', [cols*3 rows]);		elseif magic(2) == '6',			fprintf('%s: binary PPM file (%dx%d)\n', file, cols, rows)			if maxval == 1,				fmt = 'unint1';			elseif maxval == 15,				fmt = 'uint4';			elseif maxval == 255,				fmt = 'uint8';			elseif maxval == 2^32-1,				fmt = 'uint32';			end			I = fread(fid, [cols*3 rows], fmt);		else			disp('Not a PPM file');		end	end	%	% now the matrix has interleaved columns of R, G, B	%	I = I';	R = I(:,1:3:(cols*3));	G = I(:,2:3:(cols*3));	B = I(:,3:3:(cols*3));	RGB(:,:,1) = R;	RGB(:,:,2) = G;	RGB(:,:,3) = B;	fclose(fid);