> > 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? -- http://mail.python.org/mailman/listinfo/python-list
