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Re: Display ENVI image [message #38318 is a reply to message #38222]

Sat, 28 February 2004 07:26

David Fanning
Messages: 11724
Registered: August 2001

Senior Member

Ananth Kini writes:

> Could any of you tell me how to display an ENVI image using IDL
> statements *ONLY*? I have pasted a sample header of one of my images
> and few pixel values below.
> ~~~~~~~~~~~~~~~~~~~~~~~
> Header for the image :
> ~~~~~~~~~~~~~~~~~~~~~~~
> ENVI
> description = {
> Band Math Result, Expression = [b1-b2] B1:IDL Var (GRID2USE): Band
> 1:top_ne
> B2:Resize (IDL Var (GRID2USE): Band 1:dem05):dem05_ne [Tue Aug 27
> 10:50:33
> 2002]}
> samples = 911
> lines = 1025
> bands = 1
> header offset = 0
> file type = ENVI Standard
> data type = 4
> interleave = bsq
> sensor type = Unknown
> byte order = 0
> map info = {UTM, 1.000, 1.000, 267395.000, 4710962.000, 0.50000000,
> 0.50000000, 19, North, North America 1983, units=Meters}
> band names = {
> Band Math (b1-b2)}

I don't have ENVI here, but I think what this header is telling you
is that the image (which is stored in a separate file, as I understand
it) is simply a 911 by 1025 2D image of floating point (type=4) data.

To read it, you would do this:

image = FltArr(911,1025)
OpenR, lun, whateverItsNameIs, /Get_Lun
ReadU, lun, image
Free_lun, lun

That's it. Takes some of the mystery out of ENVI, doesn't it. :-)

There might be some other complications (byte ordering, etc.)
depending upon your particular IDL environment (which you don't
tell us about), but this should get you pointed in the right direction.

Cheers,

David

--
David Fanning, Ph.D.
Fanning Software Consulting
Coyote's Guide to IDL Programming: http://www.dfanning.com/

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[Message index]

		Display ENVI image By: kini on Fri, 27 February 2004 17:13
		Re: Display ENVI image By: jnettle1 on Tue, 02 March 2004 14:13
		Re: Display ENVI image By: kini on Wed, 03 March 2004 15:52
		Re: Display ENVI image By: David Fanning on Mon, 01 March 2004 18:30
		Re: Display ENVI image By: kini on Tue, 02 March 2004 16:49
		Re: Display ENVI image By: Kenneth P. Bowman on Mon, 01 March 2004 17:10
		Re: Display ENVI image By: David Fanning on Mon, 01 March 2004 14:53
		Re: Display ENVI image By: kini on Mon, 01 March 2004 14:10
		Re: Display ENVI image By: David Fanning on Sat, 28 February 2004 07:26
		Re: Display ENVI image By: David Fanning on Tue, 02 March 2004 17:03

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