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

[Indev]

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
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