so you pick up a bunch of features and do something with them.
I wish not to be so harsh but that is what the paper is. There is little justification for why a particular feature was chosen over other choices (other choices are not even mentioned). The results look impressive, but then what is the baseline ? how hard is the problem ? Is mixture of gaussians the best you can do ? Probably not. I agree with Markus, the gui looks more like a toy rather than a serious content based retrival system.