Re: [help-GIFT] Asymmetric Similarity Matrix

[Henning Müller]

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 
> <address@hidden <mailto:address@hidden>> 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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