Matlab读写ENVI.img.hdr文件2.doc

Matlab读取ENVI标准格式文件

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每个*.img文件对应一个*.hdr的头文件，程序首先从头文件里得到影像的行列和波段数，然后按照二进制方式读取，并按照行列波段数重排为多维矩阵。

function [image,p,t]=freadenvi(fname);

% freadenvi - read envi image (V. Guissard, Apr 29 2004)

% INPUT :

% fname string giving the full pathname of the ENVI image to read.

% OUTPUT :

% image : c by l by b array containing the ENVI image values organised in

%c : cols, l : lines and b : bands.

%p :1 by 3 vector that contains (1) the nb of cols, (2) the number of lines and

% (3) the number of bands of the opened image.

% t:string describing the image data type string in MATLAB conventions.

%freadenvi needs the corresponding image header file generated automatically by ENVI.

%The ENVI header file must have the same name as the ENVI image file + the '.hdf' exention.

% Parameters initialization

elements={'samples' 'lines' 'bands' 'data type'};

d={'bit8' 'int16' 'int32' 'float32' 'float64' 'uint16' 'uint32' 'int64' 'uint64'};

% Check user input

if ~ischar(fname)

error('fname should be a char string');

end

% Open ENVI header file to retreive s, l, b & d variables

rfid = fopen(strcat(fname,'.hdr'),'r');

% Check if the header file is correctly open

if rfid == -1

error('Input header file does not exist');

end;

% Read ENVI image header file

% and get p(1) : nb samples,p(2) : nb lines, p(3) : nb bands and t : data type

while 1

tline = fgetl(rfid);

if ~ischar(tline), break, end

[first,second]=strtok(tline,'=');

switch first

case elements(1)

[f,s]=strtok(second);

p(1)=str2num(s);

case elements(2)

[f,s]=strtok(second);

p(2)=str2num(s);

case elements(3)

[f,s]=strtok(second);

p(3)=str2num(s);

case elements(4)

[f,s]=strtok(second);

t=str2num(s);

switch t

case 1

t=d(1);

case 2

t=d(2);

case 3