From help-request at octave dot org Sun Jan  9 06:23:43 2005
Subject: Re: MATLAB script for parsing ENVI headers?
From: Miroslaw Kwasniak <mirek at zind dot ikem dot pwr dot wroc dot pl>
To: "help at octave dot org" <help@octave.org>
Date: Sun, 9 Jan 2005 13:25:46 +0100


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On Sat, Jan 08, 2005 at 03:45:32PM -0800, Jonathan Greenberg wrote:
> I was wondering if anyone knew of a MATLAB/Octave script which can parse an
> ENVI header file, retrieving all of the info necessary to import the file
> into MATLAB (number type, endian, samples, lines, bands, etc...)

If you wrote about ENVI by rsinc it's a simple structured text file.
I attached a prototype of function.

Example of run:

octave:1> OCTAVE_VERSION
OCTAVE_VERSION = 2.1.63

octave:2> hdr=read_envi_hdr('x.hdr'); fieldnames (hdr)
{
  [1,1] = band_names
  [2,1] = bands
  [3,1] = byte_order
  [4,1] = data_type
  [5,1] = data_type_txt
  [6,1] = description
  [7,1] = file_type
  [8,1] = fwhm
  [9,1] = header_offset
  [10,1] = interleave
  [11,1] = lines
  [12,1] = samples
  [13,1] = sensor_type
  [14,1] = spectra_names
  [15,1] = wavelength
  [16,1] = z_plot_range
}

Mirek

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## Copyright (C) 2005  Miroslaw Kwasniak (Miros\law Kwa\sniak)
##
## This file is part of Octave.
##
## Octave is free software; you can redistribute it and/or modify it
## under the terms of the GNU General Public License as published by
## the Free Software Foundation; either version 2, or (at your option)
## any later version.
##

## -*- texinfo -*-
## Reading of ENVI hdr file version 0.0002
##  at deftypefn {Function File} {@var{hdr} =} read_envi_hdr (@var{file_name})
## Reads envi hdr from file  at var{file_name} to a structure.
##  at end deftypefn

function hdr = read_envi_hdr( fname )

  data_type = { 'bit8', 'int16', 'int32', 'float32', 'float64', ...
                'uint16', 'uint32', 'int64', 'uint64'};
  num_set = ' 0123456789,.';
  
  if nargin ~= 1 ; error( 'read_envi_hdr( fname )' ); endif

  fh = fopen( fname, 'rt' );
  if fh<0; error( [" Can't open " fname ] ); endif
  l = fgetl (fh);
  if ~ strcmp( l, 'ENVI' ); fclose( fh ); error('Bad file'); endif
  
  while true

    l = fgetl (fh);
    if ~isstr( l ); break; end 

    i = index( l, '=' );
    if i == 0 ; fclose( fh ); error('Corrupted file'); endif

    name = strrep( deblank(l(1:i-1)) , ' ', '_' );

    l = l(i+1:end);
    i = index( l, '{' );
    if ~i 
      value = l;
    else
      l(i) = '';
      value = '';
      while true
        i = index( l, '}' );
        if i; l(i) = '' ; endif
        value = [ value, l ];
        if i; break end
        l = fgetl (fh);
        if ~isstr( l ); fclose( fh ); error('Corrupted file'); endif
      endwhile
    endif
  
    if isempty( setdiff( value, num_set ) )
      v = str2num( value );
      if ~isempty( v ); value = v; endif
    endif

    hdr.(name) = value;
    
  endwhile
  fclose( fh );

  if struct_contains ( hdr , 'data_type' )
    hdr.data_type_txt = data_type { hdr.data_type };
  endif

endfunction

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