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Re: IDLanROI Confusion [message #24560 is a reply to message #24557]

Wed, 04 April 2001 16:55

Mark Hadfield
Messages: 783
Registered: May 1995

Senior Member

"Craig Markwardt" <craigmnet@cow.physics.wisc.edu> wrote in message
news:onitkkcp6b.fsf@cow.physics.wisc.edu...
>
> More than likely the region of interest becomes pixelated into square
> pixels. It's pretty clear to me that this will give a greater
> perimeter than a true circle since there are more horizontal and
> vertical segments than are required.
>
> What happens if you make the circle much much bigger? I think then
> the answers will converge to what you expect.

I don't.

Consider a pixelated diagonal line segment. The length along the pixel edges
will exceed the true (along-diagonal) length by sqrt(2), however fine you
pixelate it.

---
Mark Hadfield
m.hadfield@niwa.cri.nz http://katipo.niwa.cri.nz/~hadfield
National Institute for Water and Atmospheric Research

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[Message index]

		Re: IDLanROI Confusion By: davidf on Wed, 04 April 2001 20:20
		Re: IDLanROI Confusion By: Mark Hadfield on Wed, 04 April 2001 16:55
		Re: IDLanROI Confusion By: Craig Markwardt on Wed, 04 April 2001 14:47
		Re: IDLanROI Confusion By: davidf on Thu, 05 April 2001 11:18

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