How to compare 2 different size binary images?

I need to find traffic sign in an image. I segmented the image suuccessfully, so now I got cropped binary image of the sign:

How can I check whether the sign exist in the image or not?

I tried using xcorr2, but I get better correlation comparing wrong sign.

Thanks in advance, Matanya.

Answer 1

[Image Analyst]

Sounds like a job for SIFT or SURF (in the Computer Vision System Toolbox).

See sections 15 and 22 here for papers on the topic:

http://www.visionbib.com/bibliography/contents.html

[Matanya]

Thanks for your quick reply!

Oh right, I forgot to mention that i tried using the built-in functions of surf and fast etc... but for the most of the pictures it won't find any matching features. I now tried againg, and somehow (probably there was some mistake previously) it worked like a chram.

Thanks!