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Re: Determing true resolution of an image? [message #29572]

Thu, 07 March 2002 05:51

wmconnolley
Messages: 106
Registered: November 2000

Senior Member

Martin Downing <martin.downing@ntlworld.com> wrote:
> "David Fanning" <david@dfanning.com> wrote in message
> news:MPG.16eecdf16f798ad3989831@news.frii.com...
>> William Connolley (wmc@bas.ac.uk) writes:
>>> I'd like a procedure to take a digital image (a photo) and, by in some
>>> way reducing the image and comparing the "inforamtion" left, to
> determine
>>> the "true" resolution. What I have in mind is to scan in an analogue
> photo
>>> at very high res, and to try to determine what res needs to be retained.
>>
>> What does "information" mean in this context?

Well, I'm trying to compare analogue and digital images in a quantitative way.
So "information" is the true resolution. Take an analogue image: I can scan
it in at increasingly high res, but after some level the amount of info doesn't
increase but the noise does.

> I was looking into something like this a while back, where I would interpret
> "information" as representation of the theoretical object input image
> signal. If you measure the FT of the output, you can look for the maximum
> frequency at which there is still significant power above the noise level.
> The resolution of the image could then be set to twice this frequency.

Fourier transform is an interesting idea. I'll look at that, thanks.

-W.

--
William M Connolley | wmc@bas.ac.uk | http://www.nerc-bas.ac.uk/icd/wmc/
Climate Modeller, British Antarctic Survey | Disclaimer: I speak for myself
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[Message index]

		Re: Determing true resolution of an image? By: wmconnolley on Thu, 07 March 2002 05:51
		Re: Determing true resolution of an image? By: Martin Downing on Tue, 05 March 2002 15:06
		Re: Determing true resolution of an image? By: David Fanning on Tue, 05 March 2002 11:44
		Re: Determing true resolution of an image? By: chrisduckworth on Thu, 07 March 2002 22:28

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