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Re: make a vector from all pixels in a moving window [message #74527 is a reply to message #74526]

Sat, 22 January 2011 15:59

Robin Wilson
Messages: 40
Registered: August 2010

Member

Hi Jenny,

I use the function below to do this for me. It might not be the most
efficient way of doing it (my IDL code is often lacking in terms of
efficiency), but it works:

FUNCTION GET_LOCAL_SUBSET, n, x, y, arr
; This gets the local n x n window around the given x and y values
; It will repeat edge values as needed to provide the correctly sized
; return array
;
; Altered from http://michaelgalloy.com/2006/10/10/local
; grid-points.html (Original Author: Michael Galloy)
;
; Calculate the offsets
offsets = lindgen(n) - (n - 1) / 2

; Calculate the offsets from the given x and y values
xoffsets = reform(rebin(offsets, n, n), n^2)
yoffsets = reform(rebin(offsets, n^2), n^2)

return, reform(arr[x + xoffsets, y + yoffsets],n,n)
END

See Michael's blog post (linked in the comments above) for more
information on how it works.

Hope this helps,

Robin

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		Re: make a vector from all pixels in a moving window By: envi35@yahoo.ca on Sat, 22 January 2011 16:28
		Re: make a vector from all pixels in a moving window By: Robin Wilson on Sat, 22 January 2011 15:59

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