Frequently Asked Questions

Does NFIQ 2 v2.3 produce the same scores as older versions of NFIQ 2?
- No. Some defects were discovered in the code and ISO/IEC 29794-4:2017 that were corrected in version 2.3. Code for version 2.3 now aligns with the second edition of the standard, ISO/IEC 29794-4:2024. The complete details of changes are in the NFIQ 2.3 release notes.
NFIQ 2 is a standard?
- NFIQ 2 v2.3 is one recognized reference implementation of ISO/IEC 29794-4:2024, the second edition of the Biometric Sample Quality–Finger image data international standard. Version 2.0 was a recognized reference implementation of the first version of the standard ISO/IEC 29794-4:2017, with versions 2.1 and 2.2 correcting defects discovered during editing of the standard in the interim years.

First Edition FAQ (ISO/IEC 29794-4:2017)

Do NFIQ 2 v2.1 and NFIQ 2 v2.2 produce the same scores?
- No, they do not. Some defects were discovered and corrected in image pre-processing code. Additionally, NFIQ 2.2 is able to operate on smaller images than were permitted in NFIQ 2.1. The complete details of changes are in the NFIQ 2.2 release notes.
Do NFIQ 2 v2.0 and NFIQ 2 v2.1 produce the same scores?
- No, they do not. Several defects were discovered and corrected in the quality feature computation code that result in changes to values between 2.0 and 2.1. These changes are mostly minor and do not effect overall deployment of the quality score. As of 2.1, all scores should be consistent across all platforms. As such, the conformance scores published in the widely-distributed DRAFT NFIQ 2 Report will not be produced by NFIQ 2.1. However, the scores published in the final version of the NFIQ 2 Report (NIST IR 8382) are correct.
Why are scores different between NFIQ 2 v2.1-pre and NFIQ 2 v2.1-pre.1?
- A change was made between these releases that enabled score stability on macOS 11 with ARM64 chips (M1). Changes here are incredibly minor, but do exist. We hope this is the last change to enable score stability across platforms. Additionally, NFIQ 2.1-pre.1 no longer produces empty templates when FingerJet FX OSE fails to extract features (defect since 2.0). Instead, NFIQ 2.1 will fail on these images.

How do I run NFIQ2?
- The shipping versions of NFIQ2 have several parameters. To calculate the overall NFIQ 2 value for a single image:
```
# WSQ images
./NFIQ2 SINGLE finger.wsq WSQ false false
# BMP images
./NFIQ2 SINGLE finger.bmp BMP false false
```
- If you are running on the iso_wg3 branch, the nfiq2rf.yaml must be in the current working directory.
My BMP image does not work.
- The BMP parsing in the shipping versions of the NFIQ2 binary is very minimal. It only supports 8-bit grayscale images with 256 colors and no compression. If you think your image is 8-bit and still not working, try to convert with this command using convert from ImageMagick under Linux:
```
convert INPUT.BMP -depth 8 -compress None -colorspace Gray -colors 256 BMP3:OUTPUT.bmp
```