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Re: Getting ROI data from an image [message #77865 is a reply to message #77861]

Fri, 30 September 2011 11:42

Brian Daniel
Messages: 80
Registered: July 2009

Member

On Sep 30, 1:50 pm, Rebecca Brown <rab4...@gmail.com> wrote:
> I need to extract hyperspectral data from an image ROI :
>
> The project I'm working on requires me to code strictly with IDL, so I
> cannot use ENVI calls in the final product. I am running unsupervised
> classification (K-Means), which returns a classification image with
> each pixel assigned a number from [0,..nClasses]. I want to use the
> classification image to subset the image based on ROI and get the mean
> spectra from each class. The functionality I need is probably the same
> as ENVI_GET_ROI_DATA(). My exact question is, how can I use the one-
> dimensional calls to capture ROI data from the hypersepctral data?
>
> samples = 320
> lines = 1000
> bands = 300
> classes = 15
>
> result = KMEANS(img, ITERATIONS = 4, NCLASSES = classes)
>
> FOR i = 0, nClasses-1 DO BEGIN
> loc = WHERE(result EQ i, count)
> IF count EQ 0 THEN CONTINUE
>
> ; ?
>
> ; ?
>
> ENDFOR

Look at using the HISTOGRAM function on the result variable with
REVERSE_INDICES keyword.

http://www.idlcoyote.com/tips/histogram_tutorial.html

-Brian

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[Message index]

		Re: Getting ROI data from an image By: Rebecca on Mon, 03 October 2011 06:15
		Re: Getting ROI data from an image By: David Fanning on Fri, 30 September 2011 14:32
		Re: Getting ROI data from an image By: Rebecca on Fri, 30 September 2011 14:16
		Re: Getting ROI data from an image By: David Fanning on Fri, 30 September 2011 13:41
		Re: Getting ROI data from an image By: Rebecca on Fri, 30 September 2011 12:41
		Re: Getting ROI data from an image By: David Fanning on Fri, 30 September 2011 12:19
		Re: Getting ROI data from an image By: Brian Daniel on Fri, 30 September 2011 11:42

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