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Re: Calculate the mean of many images [message #63647 is a reply to message #63646]

Sun, 16 November 2008 11:08

Chris[6]
Messages: 84
Registered: July 2008

Member

> What does finite(img) EQ 1 mean here? Can I write this statement as
> the following?

finitie(img) eq 1 will evaluate to the same thing as finite(img) - the
finite function returns a 1 or a zero depending on whether the input
is finite.

> mask = (qa EQ 1.000 and qa EQ 0.000 ) AND (finite(img) EQ 1.000 &&
> 0.000)

this statement is mutually exclusive (qa can't equal 1 and zero at the
same time). The finite part is equally problematic. I'm not sure what
you want mask to be. But anyways, once you know how to properly phrase
the logical test for your mask, I would do the following:

;- calculate the average
mask = .... logical test on QA which is TRUE for a pixel which you
want to consider ...
average_image = total(im * mask, 3) / total(mask, 3)

;- check for and pixels where there were no good images
bad = where(total(mask,3) eq 0, ct)
if ct eq 0 then average_image[bad] = !values.f_nan

maybe a good mask would look like
mask = finite(qa) if anything finite is good or,
if you want to pull out specific qa values,
mask = ((qa eq 1) or (qa eq 2))

chris

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[Message index]

		Re: Calculate the mean of many images By: Jeremy Bailin on Mon, 17 November 2008 06:35
		Re: Calculate the mean of many images By: Craig Markwardt on Sun, 16 November 2008 23:13
		Re: Calculate the mean of many images By: Wasit.Weather on Sun, 16 November 2008 16:35
		Re: Calculate the mean of many images By: David Fanning on Sun, 16 November 2008 13:04
		Re: Calculate the mean of many images By: Wasit.Weather on Sun, 16 November 2008 12:52
		Re: Calculate the mean of many images By: Craig Markwardt on Sun, 16 November 2008 12:04
		Re: Calculate the mean of many images By: Chris[6] on Sun, 16 November 2008 11:08
		Re: Calculate the mean of many images By: Wasit.Weather on Sun, 16 November 2008 10:32
		Re: Calculate the mean of many images By: Wasit.Weather on Sun, 16 November 2008 10:30
		Re: Calculate the mean of many images By: Jeremy Bailin on Sun, 16 November 2008 06:57
		Re: Calculate the mean of many images By: Craig Markwardt on Sun, 16 November 2008 00:54
		Re: Calculate the mean of many images By: greg.addr on Sun, 16 November 2008 00:08
		Re: Calculate the mean of many images By: raghuram on Mon, 17 November 2008 08:38

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