Hello,

I'm just a beginner with SQLAlchemy (and not very experienced with databases in general) so please forgive my ignorance. Also this is my first post here so I hope I'm not off-subject.

I work on image processing. It is very common for us to use large databases of images (several hundred thousands) and then use complicated (and time consuming) algorithms to compute descriptors (i.e. a vector representing some information on the image).

I already use SQLAlchemy to store the images and their relations on the DB (in fact I store only the path) and I would like to say that it is really an amazing tool. From the modelling point-of-view this part is pretty easy.

Now, the hard part is of course the descriptors. First the goal is to avoid computing them again and again. But we need flexibility.

To describe some of the concepts I think it's better to point to the OpenCV image processing library (that I use): http://opencv.willowgarage.com/documentation/cpp/features2d__feature_detection_and_descriptor_extraction.html

To sum-up:
 - images can be pre-processed
- from an image we compute several key-points (with different algorithm, parameters, etc.) - from a keypoint we compute a descriptor (with different algorithm, parameters, etc.) - key-points can be post-processed (e.g. normalize them by removing the mean and dividing by the standard deviation)

I'm not sure what does this mean in terms of relationships between objects.

Ideally, I would like to be able to select a group of images and then specify a key-point extraction algorithm and a descriptor computation algorithm to retrieve the descriptors.

So my question is: how would you model (and implement with SQLAlchemy) this kind of database?

Thanks in advance,
Mathieu

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