function  [img, header, errmsg] = nano3read(filename)
%NANO3READ  Read the header and the image from a nanoscope file.
%
%       [I, H, ERRMSG] = NANO3READ(FILENAME)
%
%       Return:     1) The header of the file, empty on error.
%                   2) The image matrix, empty on error.
%                   3) An error message if occours.
%
%    On error, an error message is returned
%    After read the file the image is 90 degree rotated
%    to be reproducible with the nanoscope.
%
%       Claudio  6 May, 1994.
%

%
% Copyright (c) 1995 by Claudio Rivetti and Mark Young
% claudio@alice.uoregon.edu,    mark@alice.uoregon.edu
%


HEADER_SIZE_NS2 = 2048;
HEADER_SIZE_NS3 = 8192;

fp = fopen(filename, 'r');

if fp == -1
   errmsg='File not found';
   return;
end

h = fread(fp, HEADER_SIZE_NS2, 'char');
h=setstr(h)';
header_size=getparameter(h, 'Data length',1);

if header_size==inf
    fclose(fp);
    errmsg='Wrong file format';
    return
end

frewind(fp);

header = fread(fp, header_size, 'char');
header = setstr(header)';
il=findstr(header, 'image list');
bs=findstr(header, '\*');
p=[];
for i=1:length(il)
  p=[p bs(max(find(bs<il(i))))];
end
p=[p find(header==26)];
p=unique(p);
nimages=length(p)-1;

if nimages==2
  type1=getparameter(header, 'Image data',1);
  type2=getparameter(header, 'Image data',2);
  msg=['In ' filename '||',...
       ' Image 1 -> ' type1 '|',...
       ' Image 2 -> ' type2 '|',...
       '|    Which one do you want to load? |'];

  r=alexdlg(msg, 'First', 'Second', 'Cancel');
elseif nimages>2
  type1=getparameter(header, 'Image data',1);
  type2=getparameter(header, 'Image data',2);
  type3=getparameter(header, 'Image data',3)
  msg=['In ' filename '||',...
       ' Image 1 -> ' type1 '|',...
       ' Image 2 -> ' type2 '|',...
       ' Image 3 -> ' type3 '|',...
       '|     Which one do you want to load? |'];

  r=alexdlg(msg, 'First', 'Second', 'Third');
end

if strcmp(r, 'Cancel')
  fclose(fp);
  return;
end
if strcmp(r, 'First'),  ni=1;end
if strcmp(r, 'Second'), ni=2;end
if strcmp(r, 'Third'),  ni=3;end
if nimages>1
  nh=[header(1:p(1)-1) header(p(ni):p(ni+1)-1)];
  header=[nh zeros(1,length(header)-length(nh))];
end

offset=getparameter(header, 'Data offset',inf);
if getparameter(header, 'Version',1) ~= inf
  s1=getparameter(header, 'Samps/line',inf);
  s2=getparameter(header, 'Number of lines',inf);
  msize=[s1 s2];
else
  msize=getparameter(header, 'Samps/line',inf);
end
fseek(fp, offset, -1);
img = fread(fp, msize, 'short', 'vaxd');
img = rot90(img);

fclose(fp);
return