Instructions

U.are.U SDK - Developer Guide 14
Developing Applications
Optionally, the fingerprint capture device can compress the image before transmitting it.
2 Another alternative is to develop software for the fingerprint capture device to capture the fingerprint image AND
extract the fingerprint features to create an FMD. The FMD is then transmitted to the server for processing, as
shown below. FMDs are 1.5K or less and so require less bandwidth and speed.
Data Compression
If you use compression to save bandwidth or storage space, there are two options:
1 U.are.U provides compression using Wavelet Scalar Quantization (WSQ). WSQ is a wavelet-based compression
standard developed by NIST specifically for fingerprint data.
2 You can compress the data yourself using a lossless compression such as PNG.
WSQ Compression
WSQ compression allows compression of 15:1 to 12:1. For more details, see Wavelet Scalar Quantization (WSQ)
Compression on page 27
.
PNG Compression
If you are using PNG as a compression algorithm. The U.are.U SDK does not support PNG compression directly, so
you would have to capture the fingerprint as a raw image and compress it to PNG. After transmission, you must
convert the PNG file back into a raw image for minutiae extraction and identification/verification.
NIST Fingerprint Image Quality (NFIQ)
The NFIQ score indicates the quality of a fingerprint sample. The U.are.U SDK provides NFIQ calculation using code
developed by NIST. The NFIQ score is in the range 1 – 5, with 1 being the best and 5 being not suitable for feature
extraction. For more details, see
NIST Fingerprint Image Quality (NFIQ) on page 28.