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Re: envi_get_data [message #58369 is a reply to message #58273]

Fri, 25 January 2008 09:18

peter.eddy@shaw.ca
Messages: 19
Registered: March 2005

Junior Member

Hi,
Typical ENVI format files are "usually" band sequential:
Array=fltarr(ns, nl, nb) as its quickest to display.
You can obtain the interleave within the ENVI_FILE_QUERY with the
keyword Interleave=interleave where bsq=0, bil=1 and bip=2 - or by
looking at the header. Next I would check the datatype of your input
file. In your code you read in the file, query the datatype create a
new float array then write the file with the datatype of your input.
What if your input was byte or integer? Since you're output is float
you could hardcode the data_type=4 (or 5 for double).

For example you could do the following:

pro cal
envi, /restore_base_save_files
envi_init, /batch_mode
envi_open_file,'F:\testinput.img',r_fid=fid
if (fid eq -1) then return
envi_file_query, fid, ns=ns, nl=nl, nb=nb, data_type=data_type, $
interleave=interleave, dims=dims
;Could have an "if" statement to check and set the interleave
map_info = envi_get_map_info(fid = fid)
;dims = [-1L, 0, ns - 1, 0, nl - 1] **you can get the dimensions from
the query above
pos=lindgen(nb)
image=fltarr(ns, nl, nb) ; storage array for multi band processing
(loop over bands)
;image2=fltarr((nb,nl,ns) ** not required
For i=0, nb-1 Do Begin
;read band and convert to float
inBand = Float(envi_get_data (fid=fid,dims=dims,pos=i)) ;read the
2d array
image[*,*,i]=inBand* 0.8 + 100 ;do processing and store in
array
Endfor
ENVI_WRITE_ENVI_FILE,image,data_type=4,nb=nb,nl=nl,ns=ns,map _info=
map_info, $
out_name='F:\testoutput.img'
END

With this method you may run into memory problems, as you are reading
by entire bands and storing the whole image. When the image gets
larger you will have to look into ENVI's tiling routines.

Hopefully this gets you started,

Pete

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[Message index]

		envi_get_data By: yychongzi on Mon, 21 January 2008 11:42
		Re: envi_get_data By: lbusett@yahoo.it on Fri, 25 January 2008 06:03
		Re: envi_get_data By: peter.eddy@shaw.ca on Fri, 25 January 2008 09:18
		Re: envi_get_data By: Jean H. on Fri, 25 January 2008 13:49
		Re: envi_get_data By: yychongzi on Fri, 25 January 2008 13:25
		Re: envi_get_data By: woods1 on Tue, 15 September 2009 00:12
		Re: envi_get_data By: Robert Moss, PhD on Mon, 14 September 2009 11:59
		Re: envi_get_data By: Andrew Rodger on Fri, 02 October 2009 06:29
		Re: envi_get_data By: woods1 on Thu, 01 October 2009 09:48
		Re: envi_get_data By: David Fanning on Wed, 30 September 2009 07:34
		Re: envi_get_data By: woods1 on Wed, 30 September 2009 07:14
		Re: envi_get_data By: wita on Wed, 30 September 2009 02:39
		Re: envi_get_data By: woods1 on Wed, 30 September 2009 01:25
		Re: envi_get_data By: woods1 on Wed, 30 September 2009 01:09
		Re: envi_get_data By: woods1 on Wed, 30 September 2009 01:02
		Re: envi_get_data By: Chris Jengo on Tue, 29 September 2009 07:40
		Re: envi_get_data By: David Fanning on Tue, 29 September 2009 06:18
		Re: envi_get_data By: lefsky@gmail.com on Mon, 12 November 2012 14:02
		Re: envi_get_data By: lefsky@gmail.com on Sun, 11 November 2012 20:22

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