Instructions

U.are.U SDK - Developer Guide 31
The JAVA API
Streaming Fingerprints
Not all readers support streaming mode. To determine if a specific reader supports this feature, get the reader
capabilities with the GetCapabilities method and check the value of the field can_stream.
The streaming methods are:
Accessing the FingerJet Engine
The Engine interface provides functionality to
• Extract fingerprint features (create FMDs),
• Identify and compare FMDs, and
• Create enrollment FMDs.
See
Understanding the Data Flow on page 11 for details on enrollment and comparison terminology and data flow.
Creating FMDs from images
The CreateFmd() method can be used in two ways:
1 Extract fingerprint minutiae from a raw image and create an FMD.
2 Extract fingerprint minutiae from an FID and create an FMD.
The following limitations are applied to the raw images and FIDs:
• 8 bits per pixel
• no padding
• square pixels (horizontal and vertical dpi are the same)
The size of the resulting FMD will vary depending on the minutiae in a specific fingerprint.
Identification and Comparison
Identify() identifies a single FMD against an array of FMDs. This function takes as inputs:
• A single view in an FMD
• An array of FMDs (each FMD can contain up to 16 views) to compare
• The desired number of candidates to return
• The threshold for False Positive Identification Rate (FPIR) that is permitted
Each time a view has a score lower than the threshold FPIR, that view is marked as a possible candidate. Then when all
possible candidates are identified (i.e., they meet the threshold), they are ranked by their score. Finally, the function
returns as many candidates as requested, based on the candidates with the lowest dissimilarity score. For a discussion
CancelCapture Cancel a pending capture
Function Description
StartStreaming Put the reader into streaming mode. In this mode, the application must call
GetStreamImage() to acquire images from the stream.
GetStreamImage Capture a fingerprint image from the streaming data.
After this function returns, the reader remains in streaming mode.
Frame selection, scoring and other image processing are not performed by this
function.
StopStreaming End streaming mode