Re: [fprint] Comparison of two fingerprint images

[Hugo "Bonstra" Grostabussiat]

On 29/01/2011 03:18, Николай Шатохин wrote:
> Wed, 26 Jan 2011 17:55:21 +0200 було написано Hugo "Bonstra"
> Grostabussiat <dw23.de...@gmail.com>:
>
>> On 01/26/2011 14:31, Николай Шатохин wrote:
>>> Wed, 26 Jan 2011 12:12:40 +0200 було написано Hugo "Bonstra"
>>> Grostabussiat <dw23.de...@gmail.com>:
>>>
>>>> On 01/26/2011 03:16, Николай Шатохин wrote:
>>>>> I need to compare two fingerprint scans saved to disk (it's need
>>>>> for my
>>>>> web-auth system which i'm developing - one image will be stored on
>>>>> server,
>>>>> second will be send by user, encrypted of course). Do libfprint
>>>>> allows
>>>>> this? If no, what function I can modify to allow this?
>>>> The code in enroll.c and verify.c in examples/ directory could be a
>>>> good
>>>> start. However, libfprint doesn't allow to compare directly two images
>>>> stored on disk, you'll need to call the internal function
>>>> fpi_img_compare_print_data() (declared in fp_internal.h) to do that.
>>>>
>>>> Regards.
>>> What is the print data? It contains image?
>> fp_print_data is a structure which contains data about scanned
>> fingerprint, data is either NBIS minutiae or raw device data, but not an
>> image. If you want to match two images, you'll have to extract minutiae
>> from both of them and compare these together.
>> libfprint uses NBIS library to extract and compare minutiae, however it
>> doesn't provide an interface for this unless you use internal functions.
>> If doing so isn't a problem for you, your program may follow this
>> pattern:
>> For image 1:
>>   img1 = fpi_img_new (size_of_image1_data)
>>   img1.width = width_for_image1
>>   img1.height = width_for_image1
>>   fpi_img_detect_minutiae (img1)
>> Do the same for image 2, and once you got minutiae for both images:
>>   match_score = fpi_img_compare_print_data (&img1, &img2)
>>   if (match_score > BOZORTH3_DEFAULT_THRESHOLD) succeed();
>>   else fail();
>>
>> All fpi_xxx function are declared in fp_internal.h, fpi_img_xxx
>> functions are defined in img.c.
>>
>> Hope this helps.
>> Regards.
>
> I wrote simple source code. I try understand how to compare two
> fingerprint from files. I cut pieces and attempted to create program,
> that will compare two fprint_datas.
> But I have some errors:
>
>
> robotex@robotex-laptop:~/sources/fprint_examples$ gcc
> load_form_disk_and_verify.c -Inbis/include `pkg-config --cflags --libs
> glib-2.0 libfprint`
> load_form_disk_and_verify.c: In function ‘fpi_img_compare_print_data’:
> load_form_disk_and_verify.c:18: error: dereferencing pointer to
> incomplete type
> load_form_disk_and_verify.c:19: error: dereferencing pointer to
> incomplete type
> load_form_disk_and_verify.c:23: error: dereferencing pointer to
> incomplete type
> load_form_disk_and_verify.c:24: error: dereferencing pointer to
> incomplete type
fprint.h does not define struct fp_print_data. You can add the
definition of struct fp_print_data from fp_internal.h to your code, that
should work.
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