Instructions

U.are.U SDK - Developer Guide 28
The C/C++ APIs
Raw WSQ Compression
In the majority of situations where WSQ data is a solution requirement, the WSQ data is expected to be in the “raw”
format. What this means is that the data contains pure WSQ specification data and no ISO/ANSI header. Below is a
code snippet showing how to generate a raw WSQ file from a captured fingerprint image data object. The generated
file can subsequently be opened in most common WSQ viewer applications.
DPUruNet.Compression.Start();
DPUruNet.Compression.SetWsqBitrate(90, 0);
/* Using Raw compression */
Fid ISOFid = captureResult.Data; //captureResult is a parameter passed into the Async capture
listener\callback and contains the captured fingerprint image data (Fid).
byte[] rawCompress = DPUruNet.Compression.CompressRaw(ISOFid.Views[0].Width, ISOFid.Views[0].Height,
500, 8, ISOFid.Views[0].RawImage, CompressionAlgorithm.COMPRESSION_WSQ_NIST);
/* Creates valid WSQ file */
File.WriteAllBytes("WSQfromRaw.wsq",rawCompress);
NIST Fingerprint Image Quality (NFIQ)
The U.are.U SDK calculates NFIQ scores for fingerprint images. This calculation is available in two ways:
1 Using code developed by NIST. This code is included within the U.are.U C/C++ API.
2 Using the WSQ1000 SDK from Aware, Inc. on the target system. If the WSQ1000 SDK is installed, the U.are.U
functions will call the WSQ1000 functions to do NFIQ calculation instead of the native NIST-based code.
Crossmatch does not redistribute the Aware WSQ1000 SDK, it must be acquired and installed separately.
dpfj_finish_compression Releases resources.
dpfj_set_wsq_bitrate
dpfj_set_wsq_size
These two specify the same thing: the size of the resulting compressed image,
and can be used interchangeably.
Setting the bitrate at 0.75 bpp to 0.9 bpp allows compression of 15:1 to 12:1.
The parameter
tolerance_aw sets the tolerance as required by the Aware
WSQ1000 SDK and it is ignored when using NIST algorithm.
dpfj_compress_fid
dpfj_compress_raw
Compress an FID or raw image, according to the requested size.
dpfj_get_processed_data Retrieve the image that was just compressed/expanded.
dpfj_expand_fid
dpfj_expand_raw
Expand a previously compressed FID or raw image.
Function Description
dpfj_quality_nfiq_from_fid
dpfj_quality_nfiq_from_raw
Calculate the NFIQ score of an FID or raw image.
NFIQ scores range from 1 to 5, with 1 being the best quality and 5 indicating that
the image is not suitable for feature extraction.