Archived posting to the Leica Users Group, 2006/04/01

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Subject: [Leica] Re: Photo comparison software
From: pdzwig at summaventures.com (Peter Dzwig)
Date: Sat Apr 1 09:52:36 2006
References: <200603252014.k2PKDXwq030584@server1.waverley.reid.org> <dec78d9f2f1a.442bf3b0@optonline.net> <10989B25DFF39D348E4B0EE5@scarborough.isc.org>

Brian,

that's the pro-approach :-)

The problem boils down to finding efficient "classifiers" to distinguish 
your 
pictures by. The trick lies in finding the correct groups of classifiers to 
make 
it (a) efficient (b) not lead you to false positives wrt your criteria. Were 
you 
suggesting redefining the primary criteria by hand/eye each time?

The interesting question is whether or not you can automate the entire 
process. 
Clearly you can for some cases, whether you can for all is another issue. 
Presumably multiple classification criteria for a group speeds it up 
exponentially by the number of criteria chosen.

Sorry list - in danger of going seriously OT!! or maybe not?

Peter Dzwig

Brian Reid wrote:
> This is a variation of a classic computer science problem. It's hard, 
> and there's no software outside international government spy agencies 
> that can do it.
> 
> The only way to make it tractable is to define a classification scheme 
> for the pictures and sort them into similarity groups. The scheme 
> doesn't matter; you can do it by color, by whether or not it contains a 
> chimney, by whether or not it contains a person, or how much of the 
> paint is peeling.
> 
> Once you've broken down the "several thousand" pictures into clusters 
> (groups whose contents are similar according to your primary criterion) 
> then pick one of those clusters and repeat the process. If the cluster 
> consists of all photographs that have a chimney at the left side or all 
> photographs that show shark teeth, find sub-categories to allow you to 
> further divide the clusters into sub-clusters.
> 
> Keep doing this until you get groups that have under about 50 pictures 
> in them. Then compare by hand; the sub-sub-clusters will be small enough 
> that you won't have any trouble finding similar pictures.
> 
> I've done this 3 or 4 times in my life, this process works.
> 
> 
> 
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> 
> 


Replies: Reply from reid at mejac.palo-alto.ca.us (Brian Reid) ([Leica] Re: Photo comparison software)
In reply to: Message from lrzeitlin at optonline.net (lrzeitlin@optonline.net) ([Leica] Re: Photo comparison software)
Message from reid at mejac.palo-alto.ca.us (Brian Reid) ([Leica] Re: Photo comparison software)