Calculate SIFT features at specific image positions

Is it possible to use ImageKeypoints[...] to calculate SIFT feature vectors at specific image coordinates?

• ImageKeypoints[] uses SURF transform, which is often superior to SIFT. But I think you would need to code up your own SIFT feature transform. – David G. Stork Feb 21 '17 at 21:45
• Is it possible to calculate SURF features at specific grid positions? I need this for feature extraction on texture image patches. – Robinaut Feb 21 '17 at 21:47
• A simple hack would be to extract the small patch of the image centered on the point in question, then apply ImageKeypoints[] with a threshold that returned a very large number of features, and choose the returned feature closest to the center. – David G. Stork Feb 21 '17 at 21:50