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Re: Rescaling byte (0-200) ndvi to -1 to 1 values [message #84534 is a reply to message #80861]

Mon, 20 May 2013 05:39

k.shemsu
Messages: 1
Registered: May 2013

Junior Member

On Thursday, July 19, 2012 11:13:32 PM UTC+3, Paul van Delst wrote:
> Hello,
>
>
>
> On 07/19/12 15:19, Narnia wrote:
>
>> Thanks a lot, Paul, that makes sense of course but (I'm a real beginner with IDL), I'm still not sure how I would
>
>> implement that as far as calling in the images and declaring that to run and scale all the images in my folder! :(
>
>
>
> Well, let's assume you already have a function that reads the image data (I can't help with that one). Let's call it
>
> "read_image" and assume it looks something like:
>
>
>
> FUNCTION Read_Image, Filename
>
> ...open file...
>
> ...read image data...
>
> RETURN, image_data
>
> END
>
>
>
> Your scaling function could look like
>
>
>
> FUNCTION Scale_Image, Input_Image
>
> output_image = FLOAT(Input_Image)
>
> output_image = (output_image - 100.0) / 100.0
>
> RETURN, output_image
>
> END
>
>
>
> Then you can loop over your filenames on the command line
>
>
>
> IDL> files = FILE_SEARCH("path/to/data/emodis.filename.*")
>
> IDL> FOR n = 0, N_ELEMENTS(files) DO BEGIN & scaled_image = Scale_Image(Read_Image(files[n])) & ...display... & ENDFOR
>
>
>
> ?
>
>
>
> cheers,
>
>
>
> paulv

Hi Paul,

I have seen your suggestion, but I don't work in IDL. Can you tell me this process in ArcGIS? Thank you in advance for your kind support. KS

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[Message index]

		Re: Rescaling byte (0-200) ndvi to -1 to 1 values By: Narnia on Fri, 20 July 2012 07:01
		Re: Rescaling byte (0-200) ndvi to -1 to 1 values By: Narnia on Fri, 20 July 2012 07:05
		Re: Rescaling byte (0-200) ndvi to -1 to 1 values By: David Fanning on Fri, 20 July 2012 06:07
		Re: Rescaling byte (0-200) ndvi to -1 to 1 values By: Narnia on Fri, 20 July 2012 06:03
		Re: Rescaling byte (0-200) ndvi to -1 to 1 values By: Paul Van Delst[1] on Thu, 19 July 2012 13:13
		Re: Rescaling byte (0-200) ndvi to -1 to 1 values By: Narnia on Thu, 19 July 2012 12:19
		Re: Rescaling byte (0-200) ndvi to -1 to 1 values By: Paul Van Delst[1] on Thu, 19 July 2012 11:41
		Re: Rescaling byte (0-200) ndvi to -1 to 1 values By: k.shemsu on Mon, 20 May 2013 05:39

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