Re: Asymmetric Similarity Matrix

Indeed, the paper:
Tversky, A. (1977). Features of similarity. Psychological Review, 84(4), 
327-352.
shows through epxeriments that our visual similarity percetion does not 
at all correspond to a metric.

Cheers, Henning


Wolfgang Müller a écrit :
> I think the Squire et al. papers from 1999 accessible from the Viper 
> site in Geneva cite a paper of Tversky's which justifies asymmetric 
> similarity matrices: What you are looking for influences your notion of 
> similarity.
> Cheers,
> Wolfgang
> 
> On Thu, Apr 16, 2009 at 8:14 AM, Henning Müller 
> <[email protected] <mailto:[email protected]>> wrote:
> 
>     Dear Juan,
> 
>     this is normal as the similarity measure of GIFT is not a metric as
>     it is based on a tf/idf weighting form text retrieval.
>     Image similarity is calculated in the space spanned by the features
>     present in the query, only. Each image has around 1500 features out
>     of 87000 possible (most of them binary features), so each image
>     potentially spans a different sub-space in which similarity is
>     calculated.
> 
>     Cheers, Henning
> 
>     Juan C. Caicedo a écrit :
> 
>         Hello everybody,
> 
>         We are building a similarity matrix of an image collection using
>         GIFT. However, we notice that this matrix is not a symmetric one.
>         Could anybody tells us what is the reason of this behaviour and
>         some hints to obtain a symmetric similarity matrix?
> 
>         Thanks in advance to all you.
> 
>         Juan C. Caicedo
> 
> 
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