Added an option to traincascade program to select the maximum number of threads…

Added an option to traincascade program to select the maximum number of threads to use during training

apps/traincascade/traincascade.cpp

@@ -13,6 +13,7 @@ int main( int argc, char* argv[] )
     int numPos    = 2000;
     int numNeg    = 1000;
     int numStages = 20;
+    int numThreads = getNumThreads();
     int precalcValBufSize = 256,
         precalcIdxBufSize = 256;
     bool baseFormatSave = false;
@@ -36,6 +37,7 @@ int main( int argc, char* argv[] )
         cout << "  [-precalcValBufSize <precalculated_vals_buffer_size_in_Mb = " << precalcValBufSize << ">]" << endl;
         cout << "  [-precalcIdxBufSize <precalculated_idxs_buffer_size_in_Mb = " << precalcIdxBufSize << ">]" << endl;
         cout << "  [-baseFormatSave]" << endl;
+        cout << "  [-numThreads <max_number_of_threads = " << numThreads << ">]" << endl;
         cascadeParams.printDefaults();
         stageParams.printDefaults();
         for( int fi = 0; fi < fc; fi++ )
@@ -82,6 +84,10 @@ int main( int argc, char* argv[] )
         {
             baseFormatSave = true;
         }
+        else if( !strcmp( argv[i], "-numThreads" ) )
+        {
+          numThreads = atoi(argv[++i]);
+        }
         else if ( cascadeParams.scanAttr( argv[i], argv[i+1] ) ) { i++; }
         else if ( stageParams.scanAttr( argv[i], argv[i+1] ) ) { i++; }
         else if ( !set )
@@ -98,6 +104,7 @@ int main( int argc, char* argv[] )
         }
     }
 
+    setNumThreads( numThreads );
     classifier.train( cascadeDirName,
                       vecName,
                       bgName,

doc/user_guide/ug_traincascade.rst

@@ -200,6 +200,12 @@ Command line arguments of ``opencv_traincascade`` application grouped by purpose
 
         This argument is actual in case of Haar-like features. If it is specified, the cascade will be saved in the old format.
 
+    * ``-numThreads <max_number_of_threads>``
+
+        Maximum number of threads to use during training. Notice that
+        the actual number of used threads may be lower, depending on
+        your machine and compilation options.
+
 #.
 
     Cascade parameters: