private double MatchBetaAngles(JiangMinutiaDescriptor target)
{
var diff0 = Angle.DifferencePi(target.Beta0, Beta0);
var diff1 = Angle.DifferencePi(target.Beta1, Beta1);
return(54 * (Math.Pow(diff0, 2) + Math.Pow(diff1, 2)) / Math.PI);
}
private double MatchRidgeCounts(JiangMinutiaDescriptor target)
{
double diff0 = Math.Abs(target.RidgeCount0 - RidgeCount0);
double diff1 = Math.Abs(target.RidgeCount1 - RidgeCount1);
return(3 * (Math.Pow(diff0, 2) + Math.Pow(diff1, 2)));
}
private double MatchDistances(JiangMinutiaDescriptor target)
{
var diff0 = Math.Abs(target.Dist0 - Dist0);
var diff1 = Math.Abs(target.Dist1 - Dist1);
return(diff0 + diff1);
}
public override JiangFeatures Extract(Bitmap image)
{
var minutiae = MinutiaeExtractor.ExtractFeatures(image);
var skeletonImg = SkeletonImageExtractor.ExtractFeatures(image);
var descriptorsList = new List <JiangMinutiaDescriptor>();
if (minutiae.Count <= 3)
{
return(new JiangFeatures(descriptorsList));
}
var mtiaIdx = new Dictionary <Minutia, int>();
for (var i = 0; i < minutiae.Count; i++)
{
mtiaIdx.Add(minutiae[i], i);
}
for (short idx = 0; idx < minutiae.Count; idx++)
{
var query = minutiae[idx];
var nearest = GetNearest(minutiae, query);
for (var i = 0; i < nearest.Length - 1; i++)
{
for (var j = i + 1; j < nearest.Length; j++)
{
var newMTriplet = new JiangMinutiaDescriptor(skeletonImg, minutiae, idx, nearest[i],
nearest[j]);
descriptorsList.Add(newMTriplet);
}
}
}
descriptorsList.TrimExcess();
return(new JiangFeatures(descriptorsList));
}
private double MatchByType(JiangMinutiaDescriptor target)
{
var diff0 = target.MainMinutia.MinutiaType == MainMinutia.MinutiaType ? 0 : 1;
var diff1 = target.NearestMtia.MinutiaType == NearestMtia.MinutiaType ? 0 : 1;
var diff2 = target.FarthestMtia.MinutiaType == FarthestMtia.MinutiaType ? 0 : 1;
return(3 * (diff0 + diff1 + diff2));
}
internal double RotationInvariantMatch(JiangMinutiaDescriptor target)
{
var distDiff = MatchDistances(target);
var alphaDiff = MatchAlphaAngles(target);
var betaDiff = MatchBetaAngles(target);
var ridgeCountDiff = MatchRidgeCounts(target);
var mtiaTypeDiff = MatchByType(target);
var dist = Math.Sqrt(distDiff + alphaDiff + betaDiff + ridgeCountDiff + mtiaTypeDiff);
return(dist < 66 ? (66 - dist) / 66 : 0);
}
private bool MatchMtiaDirections(JiangMinutiaDescriptor target)
{
var diff = Angle.DifferencePi(target.MainMinutia.Angle, MainMinutia.Angle);
if (diff >= Math.PI / 4)
{
return(false);
}
diff = Angle.DifferencePi(target.NearestMtia.Angle, NearestMtia.Angle);
if (diff >= Math.PI / 4)
{
return(false);
}
diff = Angle.DifferencePi(target.FarthestMtia.Angle, FarthestMtia.Angle);
return(!(diff >= Math.PI / 4));
}