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Re: save image from ENVI to TIFF file [message #52189]

Mon, 15 January 2007 15:07

Jeff N.
Messages: 120
Registered: April 2005

Senior Member

You don't need the loop if you're extracting consecutive bands, and you
don't really even need the call to MAKE_ARRAY(). This can often be
done in one step:

WRITE_TIFF, 'output_filename.tif', ENVI_GET_DATA(...)

The trick is to give ENVI_GET_DATA() and WRITE_TIFF() the right
keywords, and the value of those keywords depends on the size of the
input image and the size of the subset of that image you're trying to
extract. I typically use ENVI_FILE_QUERY to get the number of samples,
lines, and bands of my input image and put them in variables like ns,
nl, and nb, respectively. You can then build a DIMS array for spatial
dimensions and a POS array for band positions. So, if you wanted to
just write the first three bands of an image out to a tif file without
spatial subsetting, try something like this:

dims = [-1,0, ns - 1, 0, nl - 1]
pos = [0,1,2]
WRITE_TIFF, 'output_filename.tif', ENVI_GET_DATA(FID=fid, DIMS=dims,
POS=pos)

But, of course, you will probably need to set the TRUE keyword to
WRITE_TIFF() based on the interleave of the input data (or depending on
how you called ENVI_GET_DATA). The basic idea is that you've got to be
able to completely and correctly describe the subset of the input image
cube that you want to write out. If you do this, you shouldn't have
much trouble with either WRITE_TIFF() or with
ENVI_OUTPUT_TO_EXTERNAL_FORMAT. I'd say 95% of the time i have trouble
with this sort of task it's b/c a keyword i thought i had right is
actually wrong, so just keep working on those keywords and you'll get
it. One piece of advice: ALWAYS have both the ENVI and IDL help
running while you write code :)

Hope that helps,
Jeff

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[Message index]

		Re: save image from ENVI to TIFF file By: Jeff N. on Mon, 15 January 2007 15:07
		Re: save image from ENVI to TIFF file By: skymaxwell@gmail.com on Mon, 15 January 2007 09:29
		Re: save image from ENVI to TIFF file By: Mort Canty on Mon, 15 January 2007 06:15
		Re: save image from ENVI to TIFF file By: skymaxwell@gmail.com on Mon, 15 January 2007 02:39
		Re: save image from ENVI to TIFF file By: Jeff N. on Sun, 14 January 2007 14:32

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