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Re: Change the default dpi [message #44157 is a reply to message #44101]

Tue, 24 May 2005 08:34

James Kuyper
Messages: 425
Registered: March 2000

Senior Member

envi35@yahoo.ca wrote:
> But it seems that I can't do this in ENVI. Say my image is 512*512, I
> can only export it as a 512*512 image, I can't change the dimentions.

We have ENVI 4.1 installed; what I'm about to say may be different in
different versions of ENVI.

Select "Basic Tools" from the top menu. On the drop-down menu, select
"Resize Data (Spatial/Spectral)". Select your input file, and then hit
the "OK" button. Set the Samples/Lines numbers to match your desired
output size. Save the result in memory - if you tell it to save to a
file it will save it in an ENVI-specific format. Choose your desired
sampling method, and whether or not you want the file compressed. Hit
the "OK" button and it rebins the data in memory.

Select "File" from the top menu. On the drop-down menu, select "Save
File As". Choose JPEG2000 (old-style jpeg doesn't seem to be an
available option), and a dialog window pops up. Select the "Input File"
that corresponds to your resized image in memory. Hit the "OK" button,
and a new dialog window replaces the old one. Choose your desired
output file name and compression level. Hit the "OK" button, and you're
done.

If JPEG2000 isn't acceptable, then you have to use IDL directly, rather
than ENVI:

READ_JPEG,infilename,image
output = REBIN(image,3,newcols,newrows)
WRITE_JPEG,outfilename,output,/true

REBIN requires that each new dimension be a multiple or factor of the
corresponding dimension of the original image. If that's an
unacceptable limitation, then you can use CONGRID instead, though it's
somewhat slower.

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[Message index]

		Change the default dpi By: envi35@yahoo.ca on Fri, 20 May 2005 14:55
		Re: Change the default dpi By: James Kuyper on Tue, 24 May 2005 08:34
		Re: Change the default dpi By: envi35@yahoo.ca on Mon, 23 May 2005 21:17
		Re: Change the default dpi By: Rick Towler on Mon, 23 May 2005 15:27
		Re: Change the default dpi By: envi35@yahoo.ca on Mon, 23 May 2005 14:06
		Re: Change the default dpi By: Rick Towler on Mon, 23 May 2005 10:37

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