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Re: RMS error [message #39379 is a reply to message #39378]

Wed, 12 May 2004 07:13

Craig Markwardt
Messages: 1869
Registered: November 1996

Senior Member

David Fanning <david@dfanning.com> writes:

> Julio writes:
>
>> I'd like to calculate Root Mean Square error using a base image and a
>> secondary image. How can I do that? Clues are welcome!
>
> rms_error = Sqrt( Total((img_1 - img2)^2)/N_Elements(img_1) )

Hey David, I'll pile on too. The problem I see with the above
expression is that there could be an offset between the two images,
which you are including in your TOTAL expression, and hence biasing
the rms value. How about the following instead?

rms_error = stddev(img_1 - img2)

Craig

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Craig B. Markwardt, Ph.D. EMAIL: craigmnet@REMOVEcow.physics.wisc.edu
Astrophysics, IDL, Finance, Derivatives | Remove "net" for better response
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[Message index]

		Re: RMS error By: David Fanning on Thu, 13 May 2004 06:36
		Re: RMS error By: julio on Thu, 13 May 2004 06:22
		Re: RMS error By: Craig Markwardt on Wed, 12 May 2004 08:11
		Re: RMS error By: James Kuyper on Wed, 12 May 2004 08:02
		Re: RMS error By: Paul Van Delst[1] on Wed, 12 May 2004 07:56
		Re: RMS error By: David Fanning on Wed, 12 May 2004 07:42
		Re: RMS error By: Craig Markwardt on Wed, 12 May 2004 07:13
		Re: RMS error By: David Fanning on Tue, 11 May 2004 16:23
		Re: RMS error By: Rick Towler on Tue, 11 May 2004 15:34
		Re: RMS error By: David Fanning on Tue, 11 May 2004 14:14

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