I'm unable to create a code book for the images from the National Data Science bowl; I get a DivideByZero exception during the Compute phase.

The stack trace indicates the problem is in the ProcessImage method of the SURF detector.

I've written an easily runnable linqpad example and posted it as a GIST here: https://gist.github.com/Crisfole/bb636955891327f8b057

To reproduce:

1. Download the train.zip data files from the National Data Science bowl. (You may have to create a kaggle account to do this, TOS seem to be ok w/ practicing on their data).
2. Extract the training images somewhere on you computer.
3. Copy-Paste the Gist into Linq-Pad and replace the directory at the top of the Main() method with yours.
4. Run.