[fprint] AES 1610 support

[Daniel Drake]

wxCover wrote:
> Well... I did it but I'm not sure it worked. I haven't received any 
> confirmation or whatever. Should I retry?

I just force-subscribed you. Let me know if there are any further 
problems sending or receiving the list mail.

> Well, I've spoke too soon in my last mail! I hadn't tried to enroll and 
> verify. The images I get looks nice BUT for the moment, I have problems 
> with enrollment and verification.
> I think the main problem is that I'm not getting enough minutiae. 
> Usually, for a fingerprint that looks really nice, I get something like 
> 10~15 minutiae. And if the image is not perfect (very often), the number 
> is less than 10.

OK.

> Now, speaking about verification, I haven't manage to get it to match. 
> The scores are always low. I think this is due to the poor number of 
> minutiae.
> I don't know how to improve the situation. Is there some tweaking we can 
> do with the algorithm which calculate minutiaes ?

How low are the scores? Is there still a noticeable difference between 
scores of matching and non-matching finger scans?

The default match score is 40, but the resultant score is dependant on 
the number of detected minutiae, so for small minutiae counts it is hard 
to reach such values.

The driver can lower the match score threshold via the bz3_threshold 
attribute (e.g. aes4000 does this).

You may also want to try enlarging the image with the enlarge_factor 
attribute. Again, aes4000 does this as the binarization results were 
horrible otherwise...

The latest fprint_demo and libfprint from git will undoubtedly help you 
get a better understanding of the problems here. You can view the 
scanned image, the binarized image, and you can plot the detected 
minutiae on both.

Thanks,
Daniel