diff --git a/openbr/core/cluster.cpp b/openbr/core/cluster.cpp
index 9e87b44..44f196a 100644
--- a/openbr/core/cluster.cpp
+++ b/openbr/core/cluster.cpp
@@ -25,13 +25,12 @@
 
 #include "openbr/core/bee.h"
 #include "openbr/core/cluster.h"
+#include "openbr/plugins/openbr_internal.h"
 
-typedef QPair<int,float> Neighbor; // QPair<id,similarity>
-typedef QList<Neighbor> Neighbors;
-typedef QVector<Neighbors> Neighborhood;
+using namespace br;
 
 // Compare function used to order neighbors from highest to lowest similarity
-static bool compareNeighbors(const Neighbor &a, const Neighbor &b)
+bool br::compareNeighbors(const Neighbor &a, const Neighbor &b)
 {
     if (a.second == b.second)
         return a.first < b.first;
diff --git a/openbr/core/core.cpp b/openbr/core/core.cpp
index ce4e3bd..7926b68 100644
--- a/openbr/core/core.cpp
+++ b/openbr/core/core.cpp
@@ -715,6 +715,11 @@ void br::Deduplicate(const File &inputGallery, const File &outputGallery, const 
     else qFatal("Unable to convert deduplication threshold to float.");
 }
 
+QSharedPointer<br::Transform> br::Transform::fromComparison(const QString &algorithm)
+{
+    return AlgorithmManager::getAlgorithm(algorithm)->comparison;
+}
+
 QSharedPointer<br::Transform> br::Transform::fromAlgorithm(const QString &algorithm, bool preprocess)
 {
     if (!preprocess)
diff --git a/openbr/openbr_plugin.h b/openbr/openbr_plugin.h
index a4bde4c..76566ba 100644
--- a/openbr/openbr_plugin.h
+++ b/openbr/openbr_plugin.h
@@ -461,9 +461,9 @@ struct TemplateList : public QList<Template>
     /*!< \brief Ensure labels are in the range [0,numClasses-1]. */
     BR_EXPORT static TemplateList relabel(const TemplateList &tl, const QString &propName, bool preserveIntegers);
 
-    QList<int> indexProperty(const QString &propName, QHash<QString, int> * valueMap=NULL,QHash<int, QVariant> * reverseLookup = NULL) const;
-    QList<int> indexProperty(const QString &propName, QHash<QString, int> &valueMap, QHash<int, QVariant> &reverseLookup) const;
-    QList<int> applyIndex(const QString &propName, const QHash<QString, int> &valueMap) const;
+    BR_EXPORT QList<int> indexProperty(const QString &propName, QHash<QString, int> * valueMap=NULL,QHash<int, QVariant> * reverseLookup = NULL) const;
+    BR_EXPORT QList<int> indexProperty(const QString &propName, QHash<QString, int> &valueMap, QHash<int, QVariant> &reverseLookup) const;
+    BR_EXPORT QList<int> applyIndex(const QString &propName, const QHash<QString, int> &valueMap) const;
 
     /*!
      * \brief Returns the total number of bytes in all the templates.
@@ -1163,6 +1163,7 @@ public:
     virtual ~Transform() {}
     static Transform *make(QString str, QObject *parent); /*!< \brief Make a transform from a string. */
     static QSharedPointer<Transform> fromAlgorithm(const QString &algorithm, bool preprocess=true); /*!< \brief Retrieve an algorithm's transform. If preprocess is true, attaches a stream transform as the root of the algorithm*/
+    static QSharedPointer<Transform> fromComparison(const QString &algorithm);
 
     virtual Transform *clone() const; /*!< \brief Copy the transform. */
 
@@ -1446,6 +1447,10 @@ BR_EXPORT void Cat(const QStringList &inputGalleries, const QString &outputGalle
  */
 BR_EXPORT void Deduplicate(const File &inputGallery, const File &outputGallery, const QString &threshold);
 
+BR_EXPORT Transform *wrapTransform(Transform *base, const QString &target);
+
+BR_EXPORT Transform *pipeTransforms(QList<Transform *> &transforms);
+
 /*! @}*/
 
 } // namespace br
diff --git a/openbr/plugins/cluster.cpp b/openbr/plugins/cluster.cpp
index 24bea1f..2a57842 100644
--- a/openbr/plugins/cluster.cpp
+++ b/openbr/plugins/cluster.cpp
@@ -204,6 +204,44 @@ class RandomCentroidsTransform : public Transform
 
 BR_REGISTER(Transform, RandomCentroidsTransform)
 
+class RegInitializer : public Initializer
+{
+    Q_OBJECT
+
+    void initialize() const
+    {
+        qRegisterMetaType<br::Neighbors>();
+    }
+};
+BR_REGISTER(Initializer, RegInitializer)
+
+class CollectNNTransform : public UntrainableMetaTransform
+{
+    Q_OBJECT
+
+    Q_PROPERTY(int keep READ get_keep WRITE set_keep RESET reset_keep STORED false)
+    BR_PROPERTY(int, keep, 20)
+
+    void project(const Template &src, Template &dst) const
+    {
+        dst.file = src.file;
+        dst.m() = cv::Mat();
+        Neighbors neighbors;
+        for (int i=0; i < src.m().cols;i++) {
+            // skip self compares
+            if (i == src.file.get<int>("FrameNumber"))
+                continue;
+            neighbors.append(Neighbor(i, src.m().at<float>(0,i)));
+        }
+        int actuallyKeep = std::min(keep, neighbors.size());
+        std::partial_sort(neighbors.begin(), neighbors.begin()+actuallyKeep, neighbors.end(), compareNeighbors);
+
+        Neighbors selected = neighbors.mid(0, actuallyKeep);
+        dst.file.set("neighbors", QVariant::fromValue(selected));
+    }
+};
+BR_REGISTER(Transform, CollectNNTransform)
+
 } // namespace br
 
 #include "cluster.moc"
diff --git a/openbr/plugins/openbr_internal.h b/openbr/plugins/openbr_internal.h
index c3a8758..2d09862 100644
--- a/openbr/plugins/openbr_internal.h
+++ b/openbr/plugins/openbr_internal.h
@@ -477,9 +477,6 @@ public:
 
 void applyAdditionalProperties(const File &temp, Transform *target);
 
-Transform *wrapTransform(Transform *base, const QString &target);
-
-Transform *pipeTransforms(QList<Transform *> &transforms);
 
 inline void splitFTEs(TemplateList &src, TemplateList  &ftes)
 {
@@ -494,6 +491,12 @@ inline void splitFTEs(TemplateList &src, TemplateList  &ftes)
     }
 }
 
+typedef QPair<int,float> Neighbor; // QPair<id,similarity>
+typedef QList<Neighbor> Neighbors;
+typedef QVector<Neighbors> Neighborhood;
+
+BR_EXPORT bool compareNeighbors(const Neighbor &a, const Neighbor &b);
+
 }
 
 #endif // OPENBR_INTERNAL_H