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Re: Cannot understand a part of the IDL routine!! pls help!! [message #71061 is a reply to message #70925]

Mon, 24 May 2010 05:16

Jeremy Bailin
Messages: 618
Registered: April 2008

Senior Member

On May 23, 11:07 am, David Fanning <n...@dfanning.com> wrote:
> bala murugan writes:
>> The following is a part of the IDL routine for region grow. The
>> following three lines of code is used to define the pixels that is the
>> ROI pixels.
>> x = FINDGEN(16*16) MOD 16 + 276
>> y = LINDGEN(16*16) / 16 + 254
>> roiPixels = x + y * imgDims[0]
>
>> The question is how does it define the ROI pixels?
>> I dont see how it does........ Somebody please help me by giving a
>> simple and clear description.
>
> What is happening here is the IDL is turning one-dimensional
> image indices into two-dimensional image indices. Before
> the advent of the function Array_Indices, we always had
> to do this by hand. This code was obviously written in
> those long-ago dark days.
>
> Here is an article that explains this process in some
> detail:
>
> http://www.dfanning.com/tips/where_to_2d.html
>
> Cheers,
>
> David
>
> --
> David Fanning, Ph.D.
> Fanning Software Consulting, Inc.
> Coyote's Guide to IDL Programming:http://www.dfanning.com/
> Sepore ma de ni thui. ("Perhaps thou speakest truth.")

Incidentally, is there an in-built routine that I've missed that does
the reverse mapping (multi-D to 1D)? I know I've written my own and I
suspect others have too, but it seems like there ought to be a built-
in version.

-Jeremy.

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[Message index]

		Cannot understand a part of the IDL routine!! pls help!! By: bala murugan on Fri, 21 May 2010 14:33
		Re: Cannot understand a part of the IDL routine!! pls help!! By: Brian Daniel on Tue, 25 May 2010 12:16
		Re: Cannot understand a part of the IDL routine!! pls help!! By: Brian Daniel on Tue, 25 May 2010 12:13
		Re: Cannot understand a part of the IDL routine!! pls help!! By: Jeremy Bailin on Wed, 26 May 2010 05:51
		Re: Cannot understand a part of the IDL routine!! pls help!! By: Jeremy Bailin on Tue, 25 May 2010 06:23
		Re: Cannot understand a part of the IDL routine!! pls help!! By: Brian Daniel on Mon, 24 May 2010 11:26
		Re: Cannot understand a part of the IDL routine!! pls help!! By: Jeremy Bailin on Mon, 24 May 2010 05:16
		Re: Cannot understand a part of the IDL routine!! pls help!! By: David Fanning on Sun, 23 May 2010 09:07

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