[fprint] Quality of fingerprint matching for a new VFS5011 138a:0011 driver

[Wojciech Zabołotny]

Hi Areseniy,

It is wonderful, that you ve succeeded to write a driver for VFS5011.
I have one in my Vostro 3750, and can't use it with my Debian/Linux OS :-(.
Are the sources of your driver available for testing?
-- 
Regards,
Wojtek

2012/12/22 Arseniy Lartsev <arseniy at chalmers.se>

> Hi,
>
> I've made a driver for
> 138a:0011 Validity Sensors, Inc. VFS5011 Fingerprint Reader
> which I have in my Dell Vostro 3350 laptop. It's now at a stage of "kind of
> working", there are still a few defects left and I'm planning to publish
> it as
> soon as I fix those. Right now I'm trying to assess the driver's quality.
>
> So I've repeatedly scanned 3 different fingers, 100 times each and
> calculated
> libfprint's comparison score (as returned by fpi_img_compare_print_data)
> for
> all pairs of images.
>
> To cut the long story short, for one of the fingers 17% of comparison
> scores
> between different images of this finger were below 25, 8% below 20, 3%
> below
> 15 and 0.6% below 10. For images of different fingers, 2% scores were ≥10
> and
> 0.07% ≥15 (the highest was 18, 1 out of 12000).
>
> Do you think it's good enough? Or should I try to improve imaging quality?
> For
> example, if one enrolls the same finger 4 times (this is what windows
> software
> on my laptop does, btw) then the chance of false negative would be 0.17⁴ =
> 0.08%, and the chance of false positive, as estimated from exponential fit
> to
> the histogram, would be about 1 in 200000. Does it make sense?
>
> Here are histograms of comparison scores for images of the same finger:
> Finger 1 http://mc2-k082.mc2.chalmers.se/fprint/rindex1_cmp.png
> Finger 2 http://mc2-k082.mc2.chalmers.se/fprint/rindex2_cmp.png
> Finger 3 http://mc2-k082.mc2.chalmers.se/fprint/rmiddle_cmp.png
> And here's for images of different fingers:
> http://mc2-k082.mc2.chalmers.se/fprint/rindex2_rmiddle_cmp.png
>
> Best regards,
> Arseniy
>
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