[fprint] Verification help request (Egis Technology 1c7a:0570)

[Indev]

Did i get you right, there is no way to use my device with libfprint
matching alorythm, unless I try to use my scanner as a swipe-type one?
That's exactly what you did with your Elan driver, right?
The scan area is indeed very small.
And i am curious why does it return several images instead of one?
Isn't it simplier to process in any case, especially when it is press-type
sensor? Just saying.


2018-02-12 4:57 GMT+07:00 Igor Filatov <ia.filatov at gmail.com>:

> Hi,
>
> 1. You need to find out the correct format of returned data. By correct I
> mean the one that allows to decode an image of a fingerprint. This is
> necessary for the matching algorithm to work. The .pgm files in your repo
> don't look like fingerprints, right? They look like noise because the
> dimensions are incorrect.
> 2. Raw data is not fine. I've tried a few variant and it looks like your
> device returns 8bit 114x57 images. And it returns 5 of them together. Not
> sure, maybe the driver is supposed to combine them in some way.
> 3. libfrpint doesn't care that much about pixel dimensions. What is does
> very much care about is the physical size of the fingerptint that a device
> can scan. In your case it's very small. It won't work. Welcome to the
> club... See the recent discussions in the mailing list about the Elan
> driver I'm writing. It has the same problem tldr: libfprint uses a fp
> matching algo that detects minutiae (notable elements of a fingerprint) and
> needs to see 60+% of a print surface (from my observations, ymmv) to work
> reliably. Your reader covers maybe 15%. That's not enough. Original drivers
> for such devices for Windows, phones etc. probably have a different
> matching algo.
>
> On Sun, Feb 11, 2018 at 1:25 PM Indev <indev12 at gmail.com> wrote:
>
>> Hello,
>>
>> I am writing a driver for Egis Technology Inc. sensor (ID 1c7a:0570), but
>> having few problems.
>> First of all, i have no idea what is the model of my sensor. I've checked
>> USB.org product lists as well as manufacturer's website and Acer website (I
>> am using Acer Swift 1 SF-113-31 with this sensor integrated).
>> I failed to find any kind of information about my device and started to
>> write driver without that.
>> I was managed to recreate driver exchange process and get data from the
>> sensor.
>> This is the press-type sensor and it returns 32512 bytes of data in one
>> packet, which seem to be raw image data.
>> I don't know what is the size of the returned image, so i've picked up
>> the most suitable one for libfprint driver.
>> Couple days ago i finished libfprint driver and it works fine, except of
>> the fact that the verify_live example from libfprint is not able to do
>> correct verification. It can't recognize same finger again and allows to
>> pass verification by another finger, which is kinda funny.
>>
>> I have absolutely no experience with fingerprint scanner and I was hoping
>> that someone here could help me.
>> This is the repository of my driver: https://github.com/indev29/egis0570
>> The 'scans' directory contains examples of fingerprint scans converted
>> into different sized .pgm images as well as raw binary data, received from
>> sensor.
>> Directories names ("scans/finger_avg_NUM") indicate average color value,
>> which is more, when i press harder on sensor.
>>
>> My questions are:
>> 1. Should i use this raw image data in my libfprint driver or should i
>> process it somehow first?
>> 2. If raw data is fine, why am i not able to do verification correctly?
>> 3. Does libfprint care about image size? Can the wrong image size be the
>> thing in my case (i am using 254x128)
>>
>> Thanks in advance,
>> Indev
>> _______________________________________________
>> fprint mailing list
>> fprint at lists.freedesktop.org
>> https://lists.freedesktop.org/mailman/listinfo/fprint
>>
>
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