From f00e00ece30cbaeb7a872075507bf3554197a89c Mon Sep 17 00:00:00 2001
From: Scott Klum <scott.klum@gmail.com>
Date: Tue, 7 Jan 2014 14:42:02 -0500
Subject: [PATCH] Added ZScore distance

---
 openbr/plugins/quality.cpp | 59 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 59 insertions(+), 0 deletions(-)

diff --git a/openbr/plugins/quality.cpp b/openbr/plugins/quality.cpp
index 78fc093..dfa0a21 100644
--- a/openbr/plugins/quality.cpp
+++ b/openbr/plugins/quality.cpp
@@ -211,6 +211,65 @@ protected:
 
 BR_REGISTER(Distance, MatchProbabilityDistance)
 
+class ZScoreDistance : public Distance
+{
+    Q_OBJECT
+    Q_PROPERTY(br::Distance* distance READ get_distance WRITE set_distance RESET reset_distance STORED false)
+    Q_PROPERTY(bool crossModality READ get_crossModality WRITE set_crossModality RESET reset_crossModality STORED false)
+    BR_PROPERTY(br::Distance*, distance, make("Dist(L2)"))
+    BR_PROPERTY(bool, crossModality, false)
+
+    float min, max;
+    double mean, stddev;
+
+    void train(const TemplateList &src)
+    {
+        distance->train(src);
+
+        QScopedPointer<MatrixOutput> matrixOutput(MatrixOutput::make(FileList(src.size()), FileList(src.size())));
+        distance->compare(src, src, matrixOutput.data());
+
+        QList<float> scores;
+        scores.reserve(src.size()*src.size());
+        for (int i=0; i<src.size(); i++) {
+            for (int j=0; j<i; j++) {
+                const float score = matrixOutput.data()->data.at<float>(i, j);
+                if (score == -std::numeric_limits<float>::max()) continue;
+                if (crossModality && src[i].file.get<QString>("MODALITY") == src[j].file.get<QString>("MODALITY")) continue;
+                scores.append(score);
+            }
+        }
+
+        Common::MinMax(scores, &min, &max);
+        Common::MeanStdDev(scores, &mean, &stddev);
+
+        if (stddev == 0) qFatal("Stddev is 0.");
+    }
+
+    float compare(const Template &target, const Template &query) const
+    {
+        float score = distance->compare(target,query);
+        if      (score == -std::numeric_limits<float>::max()) score = (min - mean) / stddev;
+        else if (score ==  std::numeric_limits<float>::max()) score = (max - mean) / stddev;
+        else                                                  score = (score - mean) / stddev;
+        return score;
+    }
+
+    void store(QDataStream &stream) const
+    {
+        distance->store(stream);
+        stream << min << max << mean << stddev;
+    }
+
+    void load(QDataStream &stream)
+    {
+        distance->load(stream);
+        stream >> min >> max >> mean >> stddev;
+    }
+};
+
+BR_REGISTER(Distance, ZScoreDistance)
+
 /*!
  * \ingroup distances
  * \brief Match Probability modification for heat maps \cite klare12
--
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