image matching algorithms

[Sengly]

On Mar 14, 10:59 am, "Daniel Fetchinson" <fetchin... at googlemail.com>
wrote:
> > > Since you seem to know quite a bit about this topic, what is your
> > > opinion on the apparently 'generic' algorithm described here:
> > >http://grail.cs.washington.edu/projects/query/?
> > > So far it seems to me that it does what I'm asking for, it does even
> > > more because it can take a hand drawn sample image and query the
> > > database for similar photos.
>
> > > There is even a python implementation for it here:
> > >http://members.tripod.com/~edcjones/pycode.html
>
> > > On the histogram method I agree that it won't work partly because of
> > > what you say and partly because it is terribly slow since it's
> > > comparing every single pixel.
>
> > I'm hardly the expert and can't answer authoritatively, but here's my 2c.
>
> > I can't comment as to the actual accuracy of the algorithm, since it
> > will depend on your specific data set (set of photos). The algorithm is
> > sensitive to spatial and luminance information (because of the YIQ
> > colorspace), so there are simple ways in which it will fail.
>
> > The histogram method uses only color, but has a lot of numbers to
> > compare. You may find the histogram method insensitive to spatial
> > relations (a landscape with the mountain on the left and one with the
> > mountain on the right) compared to the wavelet approach.
>
> > This is a relatively old paper, and I've seen other more recent image
> > retrieval research using wavelets (some cases using only the
> > high-frequency wavelets for "texture" information instead of the
> > low-frequency ones used by this paper for "shape") and other information
> > retrieval-related research using lossy compressed data as the features.
> > If you have time, you may want to look at other research that cite this
> > particular paper.
>
> > And just a thought: Instead of merely cutting off at m largest-wavelets,
> > why not apply a quantization matrix to all the values?
>
> I'm not at all an expert, just started to look into image matching, so
> I'm not quite sure what you mean. What's a quantization matrix in this
> context?

Hello,

I am also looking for the solution to the same problem. Could you let
me know if you have found something useful so far?

I appreciate your response.

Thanks a lot.

Sengly