diff --git a/apps/traincascade/HOGfeatures.cpp b/apps/traincascade/HOGfeatures.cpp
index 9a562fcad0..49af05cf01 100644
--- a/apps/traincascade/HOGfeatures.cpp
+++ b/apps/traincascade/HOGfeatures.cpp
@@ -4,6 +4,8 @@
 #include "HOGfeatures.h"
 #include "cascadeclassifier.h"
 
+using namespace std;
+using namespace cv;
 
 CvHOGFeatureParams::CvHOGFeatureParams()
 {
diff --git a/apps/traincascade/HOGfeatures.h b/apps/traincascade/HOGfeatures.h
index a7f33f6086..cdf758777d 100644
--- a/apps/traincascade/HOGfeatures.h
+++ b/apps/traincascade/HOGfeatures.h
@@ -20,33 +20,33 @@ class CvHOGEvaluator : public CvFeatureEvaluator
 public:
     virtual ~CvHOGEvaluator() {}
     virtual void init(const CvFeatureParams *_featureParams,
-        int _maxSampleCount, Size _winSize );
-    virtual void setImage(const Mat& img, uchar clsLabel, int idx);
+        int _maxSampleCount, cv::Size _winSize );
+    virtual void setImage(const cv::Mat& img, uchar clsLabel, int idx);
     virtual float operator()(int varIdx, int sampleIdx) const;
-    virtual void writeFeatures( FileStorage &fs, const Mat& featureMap ) const;
+    virtual void writeFeatures( cv::FileStorage &fs, const cv::Mat& featureMap ) const;
 protected:
     virtual void generateFeatures();
-    virtual void integralHistogram(const Mat &img, vector<Mat> &histogram, Mat &norm, int nbins) const;
+    virtual void integralHistogram(const cv::Mat &img, std::vector<cv::Mat> &histogram, cv::Mat &norm, int nbins) const;
     class Feature
     {
     public:
         Feature();
         Feature( int offset, int x, int y, int cellW, int cellH );
-        float calc( const vector<Mat> &_hists, const Mat &_normSum, size_t y, int featComponent ) const;
-        void write( FileStorage &fs ) const;
-        void write( FileStorage &fs, int varIdx ) const;
+        float calc( const std::vector<cv::Mat> &_hists, const cv::Mat &_normSum, size_t y, int featComponent ) const;
+        void write( cv::FileStorage &fs ) const;
+        void write( cv::FileStorage &fs, int varIdx ) const;
 
-        Rect rect[N_CELLS]; //cells
+        cv::Rect rect[N_CELLS]; //cells
 
         struct
         {
             int p0, p1, p2, p3;
         } fastRect[N_CELLS];
     };
-    vector<Feature> features;
+    std::vector<Feature> features;
 
-    Mat normSum; //for nomalization calculation (L1 or L2)
-    vector<Mat> hist;
+    cv::Mat normSum; //for nomalization calculation (L1 or L2)
+    std::vector<cv::Mat> hist;
 };
 
 inline float CvHOGEvaluator::operator()(int varIdx, int sampleIdx) const
@@ -57,7 +57,7 @@ inline float CvHOGEvaluator::operator()(int varIdx, int sampleIdx) const
     return features[featureIdx].calc( hist, normSum, sampleIdx, componentIdx);
 }
 
-inline float CvHOGEvaluator::Feature::calc( const vector<Mat>& _hists, const Mat& _normSum, size_t y, int featComponent ) const
+inline float CvHOGEvaluator::Feature::calc( const std::vector<cv::Mat>& _hists, const cv::Mat& _normSum, size_t y, int featComponent ) const
 {
     float normFactor;
     float res;
diff --git a/apps/traincascade/boost.cpp b/apps/traincascade/boost.cpp
index 4f91d5a29d..d1a2b3e0f7 100644
--- a/apps/traincascade/boost.cpp
+++ b/apps/traincascade/boost.cpp
@@ -1,6 +1,19 @@
 #include "opencv2/core/core.hpp"
 #include "opencv2/core/internal.hpp"
 
+using cv::Size;
+using cv::Mat;
+using cv::Point;
+using cv::FileStorage;
+using cv::Rect;
+using cv::Ptr;
+using cv::FileNode;
+using cv::Mat_;
+using cv::Range;
+using cv::FileNodeIterator;
+using cv::ParallelLoopBody;
+
+
 #include "boost.h"
 #include "cascadeclassifier.h"
 #include <queue>
@@ -160,10 +173,10 @@ CvCascadeBoostParams::CvCascadeBoostParams( int _boostType,
 
 void CvCascadeBoostParams::write( FileStorage &fs ) const
 {
-    String boostTypeStr = boost_type == CvBoost::DISCRETE ? CC_DISCRETE_BOOST :
+    string boostTypeStr = boost_type == CvBoost::DISCRETE ? CC_DISCRETE_BOOST :
                           boost_type == CvBoost::REAL ? CC_REAL_BOOST :
                           boost_type == CvBoost::LOGIT ? CC_LOGIT_BOOST :
-                          boost_type == CvBoost::GENTLE ? CC_GENTLE_BOOST : String();
+                          boost_type == CvBoost::GENTLE ? CC_GENTLE_BOOST : string();
     CV_Assert( !boostTypeStr.empty() );
     fs << CC_BOOST_TYPE << boostTypeStr;
     fs << CC_MINHITRATE << minHitRate;
@@ -175,7 +188,7 @@ void CvCascadeBoostParams::write( FileStorage &fs ) const
 
 bool CvCascadeBoostParams::read( const FileNode &node )
 {
-    String boostTypeStr;
+    string boostTypeStr;
     FileNode rnode = node[CC_BOOST_TYPE];
     rnode >> boostTypeStr;
     boost_type = !boostTypeStr.compare( CC_DISCRETE_BOOST ) ? CvBoost::DISCRETE :
@@ -213,10 +226,10 @@ void CvCascadeBoostParams::printDefaults() const
 
 void CvCascadeBoostParams::printAttrs() const
 {
-    String boostTypeStr = boost_type == CvBoost::DISCRETE ? CC_DISCRETE_BOOST :
+    string boostTypeStr = boost_type == CvBoost::DISCRETE ? CC_DISCRETE_BOOST :
                           boost_type == CvBoost::REAL ? CC_REAL_BOOST :
                           boost_type == CvBoost::LOGIT  ? CC_LOGIT_BOOST :
-                          boost_type == CvBoost::GENTLE ? CC_GENTLE_BOOST : String();
+                          boost_type == CvBoost::GENTLE ? CC_GENTLE_BOOST : string();
     CV_Assert( !boostTypeStr.empty() );
     cout << "boostType: " << boostTypeStr << endl;
     cout << "minHitRate: " << minHitRate << endl;
@@ -226,7 +239,7 @@ void CvCascadeBoostParams::printAttrs() const
     cout << "maxWeakCount: " << weak_count << endl;
 }
 
-bool CvCascadeBoostParams::scanAttr( const String prmName, const String val)
+bool CvCascadeBoostParams::scanAttr( const string prmName, const string val)
 {
     bool res = true;
 
diff --git a/apps/traincascade/boost.h b/apps/traincascade/boost.h
index 16f7c2ce1d..0edf776a5b 100644
--- a/apps/traincascade/boost.h
+++ b/apps/traincascade/boost.h
@@ -13,11 +13,11 @@ struct CvCascadeBoostParams : CvBoostParams
     CvCascadeBoostParams( int _boostType, float _minHitRate, float _maxFalseAlarm,
                           double _weightTrimRate, int _maxDepth, int _maxWeakCount );
     virtual ~CvCascadeBoostParams() {}
-    void write( FileStorage &fs ) const;
-    bool read( const FileNode &node );
+    void write( cv::FileStorage &fs ) const;
+    bool read( const cv::FileNode &node );
     virtual void printDefaults() const;
     virtual void printAttrs() const;
-    virtual bool scanAttr( const String prmName, const String val);
+    virtual bool scanAttr( const std::string prmName, const std::string val);
 };
 
 struct CvCascadeBoostTrainData : CvDTreeTrainData
@@ -45,7 +45,7 @@ struct CvCascadeBoostTrainData : CvDTreeTrainData
     virtual void free_train_data();
 
     const CvFeatureEvaluator* featureEvaluator;
-    Mat valCache; // precalculated feature values (CV_32FC1)
+    cv::Mat valCache; // precalculated feature values (CV_32FC1)
     CvMat _resp; // for casting
     int numPrecalcVal, numPrecalcIdx;
 };
@@ -54,9 +54,9 @@ class CvCascadeBoostTree : public CvBoostTree
 {
 public:
     virtual CvDTreeNode* predict( int sampleIdx ) const;
-    void write( FileStorage &fs, const Mat& featureMap );
-    void read( const FileNode &node, CvBoost* _ensemble, CvDTreeTrainData* _data );
-    void markFeaturesInMap( Mat& featureMap );
+    void write( cv::FileStorage &fs, const cv::Mat& featureMap );
+    void read( const cv::FileNode &node, CvBoost* _ensemble, CvDTreeTrainData* _data );
+    void markFeaturesInMap( cv::Mat& featureMap );
 protected:
     virtual void split_node_data( CvDTreeNode* n );
 };
@@ -70,10 +70,10 @@ public:
     virtual float predict( int sampleIdx, bool returnSum = false ) const;
 
     float getThreshold() const { return threshold; }
-    void write( FileStorage &fs, const Mat& featureMap ) const;
-    bool read( const FileNode &node, const CvFeatureEvaluator* _featureEvaluator,
+    void write( cv::FileStorage &fs, const cv::Mat& featureMap ) const;
+    bool read( const cv::FileNode &node, const CvFeatureEvaluator* _featureEvaluator,
                const CvCascadeBoostParams& _params );
-    void markUsedFeaturesInMap( Mat& featureMap );
+    void markUsedFeaturesInMap( cv::Mat& featureMap );
 protected:
     virtual bool set_params( const CvBoostParams& _params );
     virtual void update_weights( CvBoostTree* tree );
diff --git a/apps/traincascade/cascadeclassifier.cpp b/apps/traincascade/cascadeclassifier.cpp
index 33f29aa7be..7c18348ae5 100644
--- a/apps/traincascade/cascadeclassifier.cpp
+++ b/apps/traincascade/cascadeclassifier.cpp
@@ -5,6 +5,7 @@
 #include <queue>
 
 using namespace std;
+using namespace cv;
 
 static const char* stageTypes[] = { CC_BOOST };
 static const char* featureTypes[] = { CC_HAAR, CC_LBP, CC_HOG };
@@ -24,10 +25,10 @@ CvCascadeParams::CvCascadeParams( int _stageType, int _featureType ) : stageType
 
 void CvCascadeParams::write( FileStorage &fs ) const
 {
-    String stageTypeStr = stageType == BOOST ? CC_BOOST : String();
+    string stageTypeStr = stageType == BOOST ? CC_BOOST : string();
     CV_Assert( !stageTypeStr.empty() );
     fs << CC_STAGE_TYPE << stageTypeStr;
-    String featureTypeStr = featureType == CvFeatureParams::HAAR ? CC_HAAR :
+    string featureTypeStr = featureType == CvFeatureParams::HAAR ? CC_HAAR :
                             featureType == CvFeatureParams::LBP ? CC_LBP :
                             featureType == CvFeatureParams::HOG ? CC_HOG :
                             0;
@@ -41,7 +42,7 @@ bool CvCascadeParams::read( const FileNode &node )
 {
     if ( node.empty() )
         return false;
-    String stageTypeStr, featureTypeStr;
+    string stageTypeStr, featureTypeStr;
     FileNode rnode = node[CC_STAGE_TYPE];
     if ( !rnode.isString() )
         return false;
@@ -96,7 +97,7 @@ void CvCascadeParams::printAttrs() const
     cout << "sampleHeight: " << winSize.height << endl;
 }
 
-bool CvCascadeParams::scanAttr( const String prmName, const String val )
+bool CvCascadeParams::scanAttr( const string prmName, const string val )
 {
     bool res = true;
     if( !prmName.compare( "-stageType" ) )
@@ -126,9 +127,9 @@ bool CvCascadeParams::scanAttr( const String prmName, const String val )
 
 //---------------------------- CascadeClassifier --------------------------------------
 
-bool CvCascadeClassifier::train( const String _cascadeDirName,
-                                const String _posFilename,
-                                const String _negFilename,
+bool CvCascadeClassifier::train( const string _cascadeDirName,
+                                const string _posFilename,
+                                const string _negFilename,
                                 int _numPos, int _numNeg,
                                 int _precalcValBufSize, int _precalcIdxBufSize,
                                 int _numStages,
@@ -411,7 +412,7 @@ bool CvCascadeClassifier::readStages( const FileNode &node)
 #define ICV_HAAR_PARENT_NAME            "parent"
 #define ICV_HAAR_NEXT_NAME              "next"
 
-void CvCascadeClassifier::save( const String filename, bool baseFormat )
+void CvCascadeClassifier::save( const string filename, bool baseFormat )
 {
     FileStorage fs( filename, FileStorage::WRITE );
 
@@ -503,7 +504,7 @@ void CvCascadeClassifier::save( const String filename, bool baseFormat )
     fs << "}";
 }
 
-bool CvCascadeClassifier::load( const String cascadeDirName )
+bool CvCascadeClassifier::load( const string cascadeDirName )
 {
     FileStorage fs( cascadeDirName + CC_PARAMS_FILENAME, FileStorage::READ );
     if ( !fs.isOpened() )
diff --git a/apps/traincascade/cascadeclassifier.h b/apps/traincascade/cascadeclassifier.h
index 6890068c21..93be478b4e 100644
--- a/apps/traincascade/cascadeclassifier.h
+++ b/apps/traincascade/cascadeclassifier.h
@@ -72,24 +72,24 @@ public:
 
     CvCascadeParams();
     CvCascadeParams( int _stageType, int _featureType );
-    void write( FileStorage &fs ) const;
-    bool read( const FileNode &node );
+    void write( cv::FileStorage &fs ) const;
+    bool read( const cv::FileNode &node );
 
     void printDefaults() const;
     void printAttrs() const;
-    bool scanAttr( const String prmName, const String val );
+    bool scanAttr( const std::string prmName, const std::string val );
 
     int stageType;
     int featureType;
-    Size winSize;
+    cv::Size winSize;
 };
 
 class CvCascadeClassifier
 {
 public:
-    bool train( const String _cascadeDirName,
-                const String _posFilename,
-                const String _negFilename,
+    bool train( const std::string _cascadeDirName,
+                const std::string _posFilename,
+                const std::string _negFilename,
                 int _numPos, int _numNeg,
                 int _precalcValBufSize, int _precalcIdxBufSize,
                 int _numStages,
@@ -99,25 +99,25 @@ public:
                 bool baseFormatSave = false );
 private:
     int predict( int sampleIdx );
-    void save( const String cascadeDirName, bool baseFormat = false );
-    bool load( const String cascadeDirName );
+    void save( const std::string cascadeDirName, bool baseFormat = false );
+    bool load( const std::string cascadeDirName );
     bool updateTrainingSet( double& acceptanceRatio );
     int fillPassedSamples( int first, int count, bool isPositive, int64& consumed );
 
-    void writeParams( FileStorage &fs ) const;
-    void writeStages( FileStorage &fs, const Mat& featureMap ) const;
-    void writeFeatures( FileStorage &fs, const Mat& featureMap ) const;
-    bool readParams( const FileNode &node );
-    bool readStages( const FileNode &node );
+    void writeParams( cv::FileStorage &fs ) const;
+    void writeStages( cv::FileStorage &fs, const cv::Mat& featureMap ) const;
+    void writeFeatures( cv::FileStorage &fs, const cv::Mat& featureMap ) const;
+    bool readParams( const cv::FileNode &node );
+    bool readStages( const cv::FileNode &node );
 
-    void getUsedFeaturesIdxMap( Mat& featureMap );
+    void getUsedFeaturesIdxMap( cv::Mat& featureMap );
 
     CvCascadeParams cascadeParams;
-    Ptr<CvFeatureParams> featureParams;
-    Ptr<CvCascadeBoostParams> stageParams;
+    cv::Ptr<CvFeatureParams> featureParams;
+    cv::Ptr<CvCascadeBoostParams> stageParams;
 
-    Ptr<CvFeatureEvaluator> featureEvaluator;
-    vector< Ptr<CvCascadeBoost> > stageClassifiers;
+    cv::Ptr<CvFeatureEvaluator> featureEvaluator;
+    std::vector< cv::Ptr<CvCascadeBoost> > stageClassifiers;
     CvCascadeImageReader imgReader;
     int numStages, curNumSamples;
     int numPos, numNeg;
diff --git a/apps/traincascade/features.cpp b/apps/traincascade/features.cpp
index effa4dcc56..a772aa39ff 100644
--- a/apps/traincascade/features.cpp
+++ b/apps/traincascade/features.cpp
@@ -5,6 +5,7 @@
 #include "cascadeclassifier.h"
 
 using namespace std;
+using namespace cv;
 
 float calcNormFactor( const Mat& sum, const Mat& sqSum )
 {
@@ -24,7 +25,7 @@ CvParams::CvParams() : name( "params" ) {}
 void CvParams::printDefaults() const
 { cout << "--" << name << "--" << endl; }
 void CvParams::printAttrs() const {}
-bool CvParams::scanAttr( const String, const String ) { return false; }
+bool CvParams::scanAttr( const string, const string ) { return false; }
 
 
 //---------------------------- FeatureParams --------------------------------------
diff --git a/apps/traincascade/haarfeatures.cpp b/apps/traincascade/haarfeatures.cpp
index 0298b42a78..d31db4fcda 100644
--- a/apps/traincascade/haarfeatures.cpp
+++ b/apps/traincascade/haarfeatures.cpp
@@ -5,6 +5,7 @@
 #include "cascadeclassifier.h"
 
 using namespace std;
+using namespace cv;
 
 CvHaarFeatureParams::CvHaarFeatureParams() : mode(BASIC)
 {
@@ -25,9 +26,9 @@ void CvHaarFeatureParams::init( const CvFeatureParams& fp )
 void CvHaarFeatureParams::write( FileStorage &fs ) const
 {
     CvFeatureParams::write( fs );
-    String modeStr = mode == BASIC ? CC_MODE_BASIC :
+    string modeStr = mode == BASIC ? CC_MODE_BASIC :
                      mode == CORE ? CC_MODE_CORE :
-                     mode == ALL ? CC_MODE_ALL : String();
+                     mode == ALL ? CC_MODE_ALL : string();
     CV_Assert( !modeStr.empty() );
     fs << CC_MODE << modeStr;
 }
@@ -40,7 +41,7 @@ bool CvHaarFeatureParams::read( const FileNode &node )
     FileNode rnode = node[CC_MODE];
     if( !rnode.isString() )
         return false;
-    String modeStr;
+    string modeStr;
     rnode >> modeStr;
     mode = !modeStr.compare( CC_MODE_BASIC ) ? BASIC :
            !modeStr.compare( CC_MODE_CORE ) ? CORE :
@@ -58,13 +59,13 @@ void CvHaarFeatureParams::printDefaults() const
 void CvHaarFeatureParams::printAttrs() const
 {
     CvFeatureParams::printAttrs();
-    String mode_str = mode == BASIC ? CC_MODE_BASIC :
+    string mode_str = mode == BASIC ? CC_MODE_BASIC :
                        mode == CORE ? CC_MODE_CORE :
                        mode == ALL ? CC_MODE_ALL : 0;
     cout << "mode: " <<  mode_str << endl;
 }
 
-bool CvHaarFeatureParams::scanAttr( const String prmName, const String val)
+bool CvHaarFeatureParams::scanAttr( const string prmName, const string val)
 {
     if ( !CvFeatureParams::scanAttr( prmName, val ) )
     {
diff --git a/apps/traincascade/haarfeatures.h b/apps/traincascade/haarfeatures.h
index 64739027a9..0894d098c3 100644
--- a/apps/traincascade/haarfeatures.h
+++ b/apps/traincascade/haarfeatures.h
@@ -18,12 +18,12 @@ public:
     CvHaarFeatureParams( int _mode );
 
     virtual void init( const CvFeatureParams& fp );
-    virtual void write( FileStorage &fs ) const;
-    virtual bool read( const FileNode &node );
+    virtual void write( cv::FileStorage &fs ) const;
+    virtual bool read( const cv::FileNode &node );
 
     virtual void printDefaults() const;
     virtual void printAttrs() const;
-    virtual bool scanAttr( const String prm, const String val);
+    virtual bool scanAttr( const std::string prm, const std::string val);
 
     int mode;
 };
@@ -32,11 +32,11 @@ class CvHaarEvaluator : public CvFeatureEvaluator
 {
 public:
     virtual void init(const CvFeatureParams *_featureParams,
-        int _maxSampleCount, Size _winSize );
-    virtual void setImage(const Mat& img, uchar clsLabel, int idx);
+        int _maxSampleCount, cv::Size _winSize );
+    virtual void setImage(const cv::Mat& img, uchar clsLabel, int idx);
     virtual float operator()(int featureIdx, int sampleIdx) const;
-    virtual void writeFeatures( FileStorage &fs, const Mat& featureMap ) const;
-    void writeFeature( FileStorage &fs, int fi ) const; // for old file fornat
+    virtual void writeFeatures( cv::FileStorage &fs, const cv::Mat& featureMap ) const;
+    void writeFeature( cv::FileStorage &fs, int fi ) const; // for old file fornat
 protected:
     virtual void generateFeatures();
 
@@ -48,13 +48,13 @@ protected:
             int x0, int y0, int w0, int h0, float wt0,
             int x1, int y1, int w1, int h1, float wt1,
             int x2 = 0, int y2 = 0, int w2 = 0, int h2 = 0, float wt2 = 0.0F );
-        float calc( const Mat &sum, const Mat &tilted, size_t y) const;
-        void write( FileStorage &fs ) const;
+        float calc( const cv::Mat &sum, const cv::Mat &tilted, size_t y) const;
+        void write( cv::FileStorage &fs ) const;
 
         bool  tilted;
         struct
         {
-            Rect r;
+            cv::Rect r;
             float weight;
         } rect[CV_HAAR_FEATURE_MAX];
 
@@ -64,10 +64,10 @@ protected:
         } fastRect[CV_HAAR_FEATURE_MAX];
     };
 
-    vector<Feature> features;
-    Mat  sum;         /* sum images (each row represents image) */
-    Mat  tilted;      /* tilted sum images (each row represents image) */
-    Mat  normfactor;  /* normalization factor */
+    std::vector<Feature> features;
+    cv::Mat  sum;         /* sum images (each row represents image) */
+    cv::Mat  tilted;      /* tilted sum images (each row represents image) */
+    cv::Mat  normfactor;  /* normalization factor */
 };
 
 inline float CvHaarEvaluator::operator()(int featureIdx, int sampleIdx) const
@@ -76,7 +76,7 @@ inline float CvHaarEvaluator::operator()(int featureIdx, int sampleIdx) const
     return !nf ? 0.0f : (features[featureIdx].calc( sum, tilted, sampleIdx)/nf);
 }
 
-inline float CvHaarEvaluator::Feature::calc( const Mat &_sum, const Mat &_tilted, size_t y) const
+inline float CvHaarEvaluator::Feature::calc( const cv::Mat &_sum, const cv::Mat &_tilted, size_t y) const
 {
     const int* img = tilted ? _tilted.ptr<int>((int)y) : _sum.ptr<int>((int)y);
     float ret = rect[0].weight * (img[fastRect[0].p0] - img[fastRect[0].p1] - img[fastRect[0].p2] + img[fastRect[0].p3] ) +
diff --git a/apps/traincascade/imagestorage.cpp b/apps/traincascade/imagestorage.cpp
index 0f749f9b01..394481b737 100644
--- a/apps/traincascade/imagestorage.cpp
+++ b/apps/traincascade/imagestorage.cpp
@@ -7,7 +7,10 @@
 #include <iostream>
 #include <fstream>
 
-bool CvCascadeImageReader::create( const String _posFilename, const String _negFilename, Size _winSize )
+using namespace std;
+using namespace cv;
+
+bool CvCascadeImageReader::create( const string _posFilename, const string _negFilename, Size _winSize )
 {
     return posReader.create(_posFilename) && negReader.create(_negFilename, _winSize);
 }
@@ -22,21 +25,21 @@ CvCascadeImageReader::NegReader::NegReader()
     stepFactor  = 0.5F;
 }
 
-bool CvCascadeImageReader::NegReader::create( const String _filename, Size _winSize )
+bool CvCascadeImageReader::NegReader::create( const string _filename, Size _winSize )
 {
-    String dirname, str;
+    string dirname, str;
     std::ifstream file(_filename.c_str());
     if ( !file.is_open() )
         return false;
 
     size_t pos = _filename.rfind('\\');
     char dlmrt = '\\';
-    if (pos == String::npos)
+    if (pos == string::npos)
     {
         pos = _filename.rfind('/');
         dlmrt = '/';
     }
-    dirname = pos == String::npos ? "" : _filename.substr(0, pos) + dlmrt;
+    dirname = pos == string::npos ? "" : _filename.substr(0, pos) + dlmrt;
     while( !file.eof() )
     {
         std::getline(file, str);
@@ -64,8 +67,8 @@ bool CvCascadeImageReader::NegReader::nextImg()
         round = round % (winSize.width * winSize.height);
         last %= count;
 
-        _offset.x = min( (int)round % winSize.width, src.cols - winSize.width );
-        _offset.y = min( (int)round / winSize.width, src.rows - winSize.height );
+        _offset.x = std::min( (int)round % winSize.width, src.cols - winSize.width );
+        _offset.y = std::min( (int)round / winSize.width, src.rows - winSize.height );
         if( !src.empty() && src.type() == CV_8UC1
                 && offset.x >= 0 && offset.y >= 0 )
             break;
@@ -126,7 +129,7 @@ CvCascadeImageReader::PosReader::PosReader()
     vec = 0;
 }
 
-bool CvCascadeImageReader::PosReader::create( const String _filename )
+bool CvCascadeImageReader::PosReader::create( const string _filename )
 {
     if ( file )
         fclose( file );
diff --git a/apps/traincascade/imagestorage.h b/apps/traincascade/imagestorage.h
index 91a4e5e87f..fb68e25cb2 100644
--- a/apps/traincascade/imagestorage.h
+++ b/apps/traincascade/imagestorage.h
@@ -3,15 +3,15 @@
 
 #include "highgui.h"
 
-using namespace cv;
+
 
 class CvCascadeImageReader
 {
 public:
-    bool create( const String _posFilename, const String _negFilename, Size _winSize );
+    bool create( const std::string _posFilename, const std::string _negFilename, cv::Size _winSize );
     void restart() { posReader.restart(); }
-    bool getNeg(Mat &_img) { return negReader.get( _img ); }
-    bool getPos(Mat &_img) { return posReader.get( _img ); }
+    bool getNeg(cv::Mat &_img) { return negReader.get( _img ); }
+    bool getPos(cv::Mat &_img) { return posReader.get( _img ); }
 
 private:
     class PosReader
@@ -19,8 +19,8 @@ private:
     public:
         PosReader();
         virtual ~PosReader();
-        bool create( const String _filename );
-        bool get( Mat &_img );
+        bool create( const std::string _filename );
+        bool get( cv::Mat &_img );
         void restart();
 
         short* vec;
@@ -35,18 +35,18 @@ private:
     {
     public:
         NegReader();
-        bool create( const String _filename, Size _winSize );
-        bool get( Mat& _img );
+        bool create( const std::string _filename, cv::Size _winSize );
+        bool get( cv::Mat& _img );
         bool nextImg();
 
-        Mat     src, img;
-        vector<String> imgFilenames;
-        Point   offset, point;
+        cv::Mat     src, img;
+        std::vector<std::string> imgFilenames;
+        cv::Point   offset, point;
         float   scale;
         float   scaleFactor;
         float   stepFactor;
         size_t  last, round;
-        Size    winSize;
+        cv::Size    winSize;
     } negReader;
 };
 
diff --git a/apps/traincascade/lbpfeatures.cpp b/apps/traincascade/lbpfeatures.cpp
index cf9bb7b245..522d90a3c1 100644
--- a/apps/traincascade/lbpfeatures.cpp
+++ b/apps/traincascade/lbpfeatures.cpp
@@ -4,6 +4,8 @@
 #include "lbpfeatures.h"
 #include "cascadeclassifier.h"
 
+using namespace cv;
+
 CvLBPFeatureParams::CvLBPFeatureParams()
 {
     maxCatCount = 256;
diff --git a/apps/traincascade/lbpfeatures.h b/apps/traincascade/lbpfeatures.h
index 30c35374d3..3e36a5887a 100644
--- a/apps/traincascade/lbpfeatures.h
+++ b/apps/traincascade/lbpfeatures.h
@@ -15,11 +15,11 @@ class CvLBPEvaluator : public CvFeatureEvaluator
 public:
     virtual ~CvLBPEvaluator() {}
     virtual void init(const CvFeatureParams *_featureParams,
-        int _maxSampleCount, Size _winSize );
-    virtual void setImage(const Mat& img, uchar clsLabel, int idx);
+        int _maxSampleCount, cv::Size _winSize );
+    virtual void setImage(const cv::Mat& img, uchar clsLabel, int idx);
     virtual float operator()(int featureIdx, int sampleIdx) const
     { return (float)features[featureIdx].calc( sum, sampleIdx); }
-    virtual void writeFeatures( FileStorage &fs, const Mat& featureMap ) const;
+    virtual void writeFeatures( cv::FileStorage &fs, const cv::Mat& featureMap ) const;
 protected:
     virtual void generateFeatures();
 
@@ -28,18 +28,18 @@ protected:
     public:
         Feature();
         Feature( int offset, int x, int y, int _block_w, int _block_h  );
-        uchar calc( const Mat& _sum, size_t y ) const;
-        void write( FileStorage &fs ) const;
+        uchar calc( const cv::Mat& _sum, size_t y ) const;
+        void write( cv::FileStorage &fs ) const;
 
-        Rect rect;
+        cv::Rect rect;
         int p[16];
     };
-    vector<Feature> features;
+    std::vector<Feature> features;
 
-    Mat sum;
+    cv::Mat sum;
 };
 
-inline uchar CvLBPEvaluator::Feature::calc(const Mat &_sum, size_t y) const
+inline uchar CvLBPEvaluator::Feature::calc(const cv::Mat &_sum, size_t y) const
 {
     const int* psum = _sum.ptr<int>((int)y);
     int cval = psum[p[5]] - psum[p[6]] - psum[p[9]] + psum[p[10]];
diff --git a/apps/traincascade/traincascade.cpp b/apps/traincascade/traincascade.cpp
index 5a969f434a..c051d3f650 100644
--- a/apps/traincascade/traincascade.cpp
+++ b/apps/traincascade/traincascade.cpp
@@ -5,11 +5,12 @@
 #include "cascadeclassifier.h"
 
 using namespace std;
+using namespace cv;
 
 int main( int argc, char* argv[] )
 {
     CvCascadeClassifier classifier;
-    String cascadeDirName, vecName, bgName;
+    string cascadeDirName, vecName, bgName;
     int numPos    = 2000;
     int numNeg    = 1000;
     int numStages = 20;
diff --git a/apps/traincascade/traincascade_features.h b/apps/traincascade/traincascade_features.h
index 019a4b9b37..dfba7a3d43 100644
--- a/apps/traincascade/traincascade_features.h
+++ b/apps/traincascade/traincascade_features.h
@@ -30,13 +30,13 @@
     (p3) = (rect).x + (rect).width - (rect).height                        \
            + (step) * ((rect).y + (rect).width + (rect).height);
 
-float calcNormFactor( const Mat& sum, const Mat& sqSum );
+float calcNormFactor( const cv::Mat& sum, const cv::Mat& sqSum );
 
 template<class Feature>
-void _writeFeatures( const vector<Feature> features, FileStorage &fs, const Mat& featureMap )
+void _writeFeatures( const std::vector<Feature> features, cv::FileStorage &fs, const cv::Mat& featureMap )
 {
     fs << FEATURES << "[";
-    const Mat_<int>& featureMap_ = (const Mat_<int>&)featureMap;
+    const cv::Mat_<int>& featureMap_ = (const cv::Mat_<int>&)featureMap;
     for ( int fi = 0; fi < featureMap.cols; fi++ )
         if ( featureMap_(0, fi) >= 0 )
         {
@@ -53,13 +53,13 @@ public:
     CvParams();
     virtual ~CvParams() {}
     // from|to file
-    virtual void write( FileStorage &fs ) const = 0;
-    virtual bool read( const FileNode &node ) = 0;
+    virtual void write( cv::FileStorage &fs ) const = 0;
+    virtual bool read( const cv::FileNode &node ) = 0;
     // from|to screen
     virtual void printDefaults() const;
     virtual void printAttrs() const;
-    virtual bool scanAttr( const String prmName, const String val );
-    String name;
+    virtual bool scanAttr( const std::string prmName, const std::string val );
+    std::string name;
 };
 
 class CvFeatureParams : public CvParams
@@ -68,9 +68,9 @@ public:
     enum { HAAR = 0, LBP = 1, HOG = 2 };
     CvFeatureParams();
     virtual void init( const CvFeatureParams& fp );
-    virtual void write( FileStorage &fs ) const;
-    virtual bool read( const FileNode &node );
-    static Ptr<CvFeatureParams> create( int featureType );
+    virtual void write( cv::FileStorage &fs ) const;
+    virtual bool read( const cv::FileNode &node );
+    static cv::Ptr<CvFeatureParams> create( int featureType );
     int maxCatCount; // 0 in case of numerical features
     int featSize; // 1 in case of simple features (HAAR, LBP) and N_BINS(9)*N_CELLS(4) in case of Dalal's HOG features
 };
@@ -80,25 +80,25 @@ class CvFeatureEvaluator
 public:
     virtual ~CvFeatureEvaluator() {}
     virtual void init(const CvFeatureParams *_featureParams,
-                      int _maxSampleCount, Size _winSize );
-    virtual void setImage(const Mat& img, uchar clsLabel, int idx);
-    virtual void writeFeatures( FileStorage &fs, const Mat& featureMap ) const = 0;
+                      int _maxSampleCount, cv::Size _winSize );
+    virtual void setImage(const cv::Mat& img, uchar clsLabel, int idx);
+    virtual void writeFeatures( cv::FileStorage &fs, const cv::Mat& featureMap ) const = 0;
     virtual float operator()(int featureIdx, int sampleIdx) const = 0;
-    static Ptr<CvFeatureEvaluator> create(int type);
+    static cv::Ptr<CvFeatureEvaluator> create(int type);
 
     int getNumFeatures() const { return numFeatures; }
     int getMaxCatCount() const { return featureParams->maxCatCount; }
     int getFeatureSize() const { return featureParams->featSize; }
-    const Mat& getCls() const { return cls; }
+    const cv::Mat& getCls() const { return cls; }
     float getCls(int si) const { return cls.at<float>(si, 0); }
 protected:
     virtual void generateFeatures() = 0;
 
     int npos, nneg;
     int numFeatures;
-    Size winSize;
+    cv::Size winSize;
     CvFeatureParams *featureParams;
-    Mat cls;
+    cv::Mat cls;
 };
 
 #endif