[fprint] Digital persona u.are.u 4000 bad image

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Hello, I'm using Debian 9 64 bit when I try to scan from the digital
persona u.are.u 4000 (Model No. URU4S-U1, Part No. 50006-001,

I get the following image: https://ibb.co/e92rwn

I run the code example img_capture.c.
Is it a device problem or is it a libfprint problem?
Thank you in advance.
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