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Documentation Index

Fetch the complete documentation index at: https://mintlify.com/usnistgov/NFIQ2/llms.txt

Use this file to discover all available pages before exploring further.

NFIQ 2 uses string identifiers to reference quality measure algorithms, individual quality measures, and actionable quality feedback values. These identifiers are defined in the NFIQ2::Identifiers namespace.

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Functions

Three functions retrieve all available identifiers as string vectors:

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getActionableQualityFeedbackIDs

std::vector<std::string> getActionableQualityFeedbackIDs();
Obtain all actionable quality feedback identifiers.
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return
std::vector<std::string>
Vector of strings containing all actionable quality feedback identifiers. These correspond to constants in NFIQ2::Identifiers::ActionableQualityFeedback.
Example: 
#include <nfiq2_qualitymeasures.hpp>

auto feedbackIds = NFIQ2::QualityMeasures::getActionableQualityFeedbackIDs();

for (const auto &id : feedbackIds) {
    std::cout << "Feedback ID: " << id << std::endl;
}

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getNativeQualityMeasureAlgorithmIDs

std::vector<std::string> getNativeQualityMeasureAlgorithmIDs();
Obtain all native quality measure algorithm identifiers.
​
return
std::vector<std::string>
Vector of strings with all quality measure algorithm identifiers. These correspond to constants in NFIQ2::Identifiers::QualityMeasureAlgorithms.
Example: 
auto algorithmIds = NFIQ2::QualityMeasures::getNativeQualityMeasureAlgorithmIDs();

std::cout << "Available quality measure algorithms:" << std::endl;
for (const auto &id : algorithmIds) {
    std::cout << "  - " << id << std::endl;
}

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getNativeQualityMeasureIDs

std::vector<std::string> getNativeQualityMeasureIDs();
Obtain all quality measure identifiers from quality measure algorithms.
​
return
std::vector<std::string>
Vector of strings containing all quality measure identifiers. These correspond to constants in NFIQ2::Identifiers::QualityMeasures namespace and its sub-namespaces.
Example: 
auto measureIds = NFIQ2::QualityMeasures::getNativeQualityMeasureIDs();

std::cout << "Total quality measures: " << measureIds.size() << std::endl;
for (const auto &id : measureIds) {
    std::cout << "  - " << id << std::endl;
}

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Identifier Reference

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Quality Measure Algorithms

Defined in NFIQ2::Identifiers::QualityMeasureAlgorithms:
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FrequencyDomainAnalysis
string
Identifier for the FrequencyDomainAnalysis quality measure algorithm. Analyzes the frequency of the sinusoid following the ridge-valley structure.
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MinutiaeCount
string
Identifier for the MinutiaeCount quality measure algorithm. Counts minutiae in the image using FingerJet FX OSE.
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MinutiaeQuality
string
Identifier for the MinutiaeQuality quality measure algorithm. Assesses quality characteristics of detected minutiae.
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LocalClarity
string
Identifier for the LocalClarity quality measure algorithm. Measures the clarity of ridge and valleys.
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Contrast
string
Identifier for the Contrast quality measure algorithm. Analyzes gray level contrast.
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OrientationCertainty
string
Identifier for the OrientationCertainty quality measure algorithm. Measures strength of energy concentration along dominant ridge flow.
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OrientationFlow
string
Identifier for the OrientationFlow quality measure algorithm. Assesses ridge flow continuity.
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RegionOfInterestMean
string
Identifier for the RegionOfInterestMean quality measure algorithm. Analyzes mean grayscale value of ROI.
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RegionOfInterestCoherence
string
Identifier for the RegionOfInterestCoherence quality measure algorithm. Measures coherence in the ROI.
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RidgeValleyUniformity
string
Identifier for the RidgeValleyUniformity quality measure algorithm. Measures consistency of ridge and valley widths.

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Actionable Quality Feedback

Defined in NFIQ2::Identifiers::ActionableQualityFeedback:
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EmptyImageOrContrastTooLow
string
The image is blank or the contrast is too low. The mean gray level appears white.Threshold: Compare against NFIQ2::Thresholds::ActionableQualityFeedback::EmptyImageOrContrastTooLow
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UniformImage
string
Standard deviation of gray levels in image indicates uniformity (lack of variation).Threshold: Compare against NFIQ2::Thresholds::ActionableQualityFeedback::UniformImage
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FingerprintImageWithMinutiae
string
Number of minutiae in the image. Equivalent to the minutiae count quality measure.Threshold: Compare against NFIQ2::Thresholds::ActionableQualityFeedback::FingerprintImageWithMinutiaeNote: Equivalent to QualityMeasures::Algorithms::Minutiae::Count
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SufficientFingerprintForeground
string
Number of pixels in the computed foreground (region of interest).Threshold: Compare against NFIQ2::Thresholds::ActionableQualityFeedback::SufficientFingerprintForeground

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Quality Measures

Defined in NFIQ2::Identifiers::QualityMeasures and sub-namespaces. Quality measures are organized by algorithm:
Namespace: NFIQ2::Identifiers::QualityMeasures::FrequencyDomainAnalysis
  • Mean - Mean of local quality value
  • StdDev - Standard deviation of local quality values
  • Histogram::Bin0 through Histogram::Bin9 - Ten histogram bin boundaries
Namespace: NFIQ2::Identifiers::QualityMeasures::Minutiae
  • Count - Number of minutiae in the image
  • CountCOM - Number of minutiae in 200x200 pixel rectangle centered at center of mass
  • PercentImageMean50 - Percentage of minutiae with quality value (by Contrast::Mean) between 0-0.5
  • PercentOrientationCertainty80 - Percentage of minutiae with orientation certainty level above 80
Namespace: NFIQ2::Identifiers::QualityMeasures::RegionOfInterest
  • Mean - Mean grayscale value of local regions with at least 1 pixel in ROI
  • CoherenceSum - Sum of coherence values over all local regions within ROI
  • CoherenceMean - Average coherence (CoherenceSum divided by number of local regions in ROI)
Namespace: NFIQ2::Identifiers::QualityMeasures::LocalClarity
  • Mean - Mean of local quality value
  • StdDev - Standard deviation of local quality values
  • Histogram::Bin0 through Histogram::Bin9 - Ten histogram bin boundaries
Namespace: NFIQ2::Identifiers::QualityMeasures::Contrast
  • ImageMean - Arithmetic mean of the image (MU)
  • MeanOfBlockMeans - Arithmetic mean of per-block means (MMB)
Namespace: NFIQ2::Identifiers::QualityMeasures::OrientationCertainty
  • Mean - Mean of local quality value
  • StdDev - Standard deviation of local quality values
  • Histogram::Bin0 through Histogram::Bin9 - Ten histogram bin boundaries
Namespace: NFIQ2::Identifiers::QualityMeasures::OrientationFlow
  • Mean - Mean of local quality value
  • StdDev - Standard deviation of local quality values
  • Histogram::Bin0 through Histogram::Bin9 - Ten histogram bin boundaries
Namespace: NFIQ2::Identifiers::QualityMeasures::RidgeValleyUniformity
  • Mean - Mean of local quality value
  • StdDev - Standard deviation of local quality values
  • Histogram::Bin0 through Histogram::Bin9 - Ten histogram bin boundaries

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Usage Examples

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Listing All Identifiers

#include <nfiq2_qualitymeasures.hpp>
#include <iostream>

int main() {
    // List all quality measure algorithms
    auto algorithms = NFIQ2::QualityMeasures::getNativeQualityMeasureAlgorithmIDs();
    std::cout << "Quality Measure Algorithms (" << algorithms.size() << "):" << std::endl;
    for (const auto &id : algorithms) {
        std::cout << "  - " << id << std::endl;
    }
    
    // List all quality measures
    auto measures = NFIQ2::QualityMeasures::getNativeQualityMeasureIDs();
    std::cout << "\nQuality Measures (" << measures.size() << "):" << std::endl;
    for (const auto &id : measures) {
        std::cout << "  - " << id << std::endl;
    }
    
    // List all actionable feedback
    auto feedback = NFIQ2::QualityMeasures::getActionableQualityFeedbackIDs();
    std::cout << "\nActionable Feedback (" << feedback.size() << "):" << std::endl;
    for (const auto &id : feedback) {
        std::cout << "  - " << id << std::endl;
    }
    
    return 0;
}

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Validating Identifiers

// Check if a specific identifier is valid
std::string targetId = "FrequencyDomainAnalysis";
auto algorithmIds = NFIQ2::QualityMeasures::getNativeQualityMeasureAlgorithmIDs();

if (std::find(algorithmIds.begin(), algorithmIds.end(), targetId) != algorithmIds.end()) {
    std::cout << targetId << " is a valid algorithm identifier" << std::endl;
} else {
    std::cerr << targetId << " is not a valid algorithm identifier" << std::endl;
}

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Using Identifiers to Access Values

NFIQ2::FingerprintImageData image(data, size, width, height, 0, 500);

// Compute quality measures
auto measures = NFIQ2::QualityMeasures::computeNativeQualityMeasures(image);

// Access specific measures using constant identifiers
if (measures.find("OrientationCertainty_Mean") != measures.end()) {
    double ocMean = measures["OrientationCertainty_Mean"];
    std::cout << "Orientation Certainty Mean: " << ocMean << std::endl;
}

// Compute actionable feedback
auto feedback = NFIQ2::QualityMeasures::computeActionableQualityFeedback(image);

// Check actionable feedback values
for (const auto &id : NFIQ2::QualityMeasures::getActionableQualityFeedbackIDs()) {
    if (feedback.find(id) != feedback.end()) {
        std::cout << id << ": " << feedback[id] << std::endl;
    }
}

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Generating Reports

// Generate comprehensive quality report
NFIQ2::FingerprintImageData image(data, size, width, height, 0, 500);

auto measures = NFIQ2::QualityMeasures::computeNativeQualityMeasures(image);
auto feedback = NFIQ2::QualityMeasures::computeActionableQualityFeedback(image);

std::cout << "=== Quality Measures Report ===" << std::endl;
for (const auto &id : NFIQ2::QualityMeasures::getNativeQualityMeasureIDs()) {
    if (measures.find(id) != measures.end()) {
        std::cout << id << ": " << measures[id] << std::endl;
    }
}

std::cout << "\n=== Actionable Feedback ===" << std::endl;
for (const auto &id : NFIQ2::QualityMeasures::getActionableQualityFeedbackIDs()) {
    if (feedback.find(id) != feedback.end()) {
        std::cout << id << ": " << feedback[id] << std::endl;
    }
}

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Constants Reference

For the actual string constant values and C++ namespace structure, refer to:
  • Header file: nfiq2_constants.hpp
  • Namespace: NFIQ2::Identifiers
  • Sub-namespaces:
    • NFIQ2::Identifiers::QualityMeasureAlgorithms
    • NFIQ2::Identifiers::QualityMeasures
    • NFIQ2::Identifiers::ActionableQualityFeedback
Use the getter functions (getActionableQualityFeedbackIDs(), getNativeQualityMeasureAlgorithmIDs(), getNativeQualityMeasureIDs()) to programmatically discover available identifiers at runtime.

Quality Measures

Core functions for computing quality measures

Quality Measure Algorithms

Learn about the Algorithm class and related functions

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