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Re: image subtraction [message #29775 is a reply to message #11675]

Thu, 14 March 2002 08:00

Dick Jackson
Messages: 347
Registered: August 1998

Senior Member

"Kenneth P. Bowman" <kpb@null.com> :
>
>>>> imgArr = lonarr(12,512,512)
>
> Using the methods suggested previously, this is likely to be faster (due
> to better cache use) if you can dimension this array as
>
> imgArr = LONARR(512,512,12)

Good thinking, Ken, if this is an option for Art.
To round out the timings (YMMV):

FOR ii=0,11 DO imgArr[ii,*,*] = imgArr[ii,*,*] - img1 : 1.402 s

FOR ii=0,11 DO imgArr[ii,0,0] = imgArr[ii,*,*] - img1 : 1.232 s

FOR ii=0,11 DO imgArr[*,*,ii] = imgArr[*,*,ii] - img1 : 0.741 s

FOR ii=0,11 DO imgArr[0,0,ii] = imgArr[0,0,ii] - img1 : 0.301 s

A big win there!

For completeness:
imgarr = imgarr - rebin(reform(img1,1,512,512),12,512,512) : 0.210 s

Cheers,
--
-Dick

Dick Jackson / dick@d-jackson.com
D-Jackson Software Consulting / http://www.d-jackson.com
Calgary, Alberta, Canada / +1-403-242-7398 / Fax: 241-7392

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[Message index]

		Image subtraction By: FRANCOIS LAROSE on Mon, 18 May 1998 00:00
		Re: Image subtraction By: noname on Tue, 26 May 1998 00:00
		Re: image subtraction By: Dick Jackson on Mon, 18 March 2002 21:45
		Re: image subtraction By: K. Bowman on Sun, 17 March 2002 08:11
		Re: image subtraction By: Dick Jackson on Thu, 14 March 2002 08:00
		Re: image subtraction By: Kenneth P. Bowman on Thu, 14 March 2002 04:55
		Re: image subtraction By: Dick Jackson on Wed, 13 March 2002 18:48
		Re: image subtraction By: Craig Markwardt on Wed, 13 March 2002 16:21

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