SIFT: Scale Invariant Feature Transform

Library Reference: ccv_sift.c

What’s SIFT?

SIFT paper refers to: Distinctive Image Features from Scale-Invariant Keypoints, David G. Lowe

The current implementation in ccv was largely influenced by VLFeat: http://www.vlfeat.org/

How to run the sample program?

There is a sample program under bin/siftmatch that at your disposal, to run it, just simply type:

./siftmatch ../samples/book.png ../samples/scene.png

The output may not be most interesting thing for you, want to see some images? There is siftdraw.rb script to do that, pipe the command:

./siftmatch ../samples/book.png ../samples/scene.png | ./siftdraw.rb ../samples/book.png ../samples/scene.png output.png

Check out output.png, there are interesting lines between the book and the scene.

There is a way to show more amazing result, but with a little external help, a program called homest (http://www.ics.forth.gr/~lourakis/homest/), it may requires levmar program (http://www.ics.forth.gr/~lourakis/levmar/) as well. compile homest until you get the homest_demo binary somewhere, and pipe the command like this:

./siftmatch ../samples/book.png ../samples/scene.png | ./siftdraw.rb ../samples/book.png ../samples/scene.png output.png <directory to homest>/homest_demo

You see, somehow, SIFT recognized the book in the scene, amazing, ah?

I haven’t decided yet that if I need to include some functions like ccv_find_homography in the future release, homest is a good research package but for industrial use, I have some doubts.

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