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Re: Image analysis and ring identification [message #30277 is a reply to message #30275]

Thu, 18 April 2002 05:37

Paul Van Delst[1]
Messages: 1157
Registered: April 2002

Senior Member

Rachel Pepper wrote:
>
> Actually, the rings often have a bright spot that is not in the center of
> the ring, so I don't think the centroiding technique will work. Do you have
> any other suggestions?

Once you've isolated the region of interest within the ring (the hardest part I reckon), can't
you just determine the bright spot location by finding it's location via MAX using the image
intensities?

e.g. if the variable blob_index contains the indices of the pixels blob_image within the ring,
then

max_spot_value = MAX( blob_image[ blob_index ], max_spot_index )

Doesn't matter where the bright spot is. Or, if you're looking for regions where the
intensities are greater than some value, say max_spot_threshold, use WHERE:

max_spot_index = WHERE( blob_image[ blob_index ] GT max_spot_threshold, max_spot_count )

IF ( max_spot_count EQ 0 ) THEN $
MESSAGE, 'No bright spot found!'

In both cases, of course, max_spot_index references the blob_index array, not the actual image
array.

?

paulv

--
Paul van Delst Religious and cultural
CIMSS @ NOAA/NCEP purity is a fundamentalist
Ph: (301)763-8000 x7274 fantasy
Fax:(301)763-8545 V.S.Naipaul

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[Message index]

		Re: Image analysis and ring identification By: James Kuyper on Thu, 18 April 2002 08:07
		Re: Image analysis and ring identification By: Paul Van Delst[1] on Thu, 18 April 2002 06:44
		Re: Image analysis and ring identification By: David Fanning on Thu, 18 April 2002 06:05
		Re: Image analysis and ring identification By: Paul Van Delst[1] on Thu, 18 April 2002 05:37
		Re: Image analysis and ring identification By: Rachel Pepper on Wed, 17 April 2002 21:21
		Re: Image analysis and ring identification By: David Fanning on Wed, 17 April 2002 07:29
		Re: Image analysis and ring identification By: Dan Larson on Thu, 18 April 2002 08:37
		Re: Image analysis and ring identification By: David Fanning on Thu, 18 April 2002 08:33

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