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Re: STANDARD DEVIATON [message #20947 is a reply to message #20946]

Tue, 01 August 2000 00:00

Benno Puetz
Messages: 16
Registered: March 2000

Junior Member

Alex Schuster wrote:

> For some 3x3 pixels x_i (and a mean of x_mean), the standard deviation
> is
> s = 1/9 * sqrt( sum( (x_i-x_mean)^2 ) ). img=img-smooth(img,3) does the
> inner subtraction of the x_means,

unfortunately, that's not quite true (except for special cases) since the x_i
get only their respective mean subtracted, not the center pixel mean. I came
up with the same solution initially but it would not stand the test ...

haven't had a better idea since :(

--
Benno Puetz
Kernspintomographie
Max-Planck-Institut f. Psychiatrie Tel.: +49-89-30622-413
Kraepelinstr. 10 Fax : +49-89-30622-520
80804 Muenchen, Germany

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[Message index]

		Re: STANDARD DEVIATON By: Struan Gray on Tue, 01 August 2000 00:00
		Re: STANDARD DEVIATON By: Benno Puetz on Tue, 01 August 2000 00:00
		Re: STANDARD DEVIATON By: Struan Gray on Tue, 01 August 2000 00:00
		Re: STANDARD DEVIATON By: Alex Schuster on Tue, 01 August 2000 00:00

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