Merge pull request #1403 from lluisgomez:scene_text_detection_NM_fix

modules/objdetect/include/opencv2/objdetect/erfilter.hpp

@@ -172,8 +172,8 @@ public:
     \param  minProbability    The minimum probability difference between local maxima and local minima ERs
 */
 CV_EXPORTS Ptr<ERFilter> createERFilterNM1(const Ptr<ERFilter::Callback>& cb = Ptr<ERFilter::Callback>(),
-                                                  int thresholdDelta = 1, float minArea = 0.000025,
-                                                  float maxArea = 0.13, float minProbability = 0.2,
+                                                  int thresholdDelta = 1, float minArea = 0.00025,
+                                                  float maxArea = 0.13, float minProbability = 0.4,
                                                   bool nonMaxSuppression = true,
                                                   float minProbabilityDiff = 0.1);
 
@@ -191,7 +191,7 @@ CV_EXPORTS Ptr<ERFilter> createERFilterNM1(const Ptr<ERFilter::Callback>& cb = P
     \param  minProbability The minimum probability P(er|character) allowed for retreived ER's
 */
 CV_EXPORTS Ptr<ERFilter> createERFilterNM2(const Ptr<ERFilter::Callback>& cb = Ptr<ERFilter::Callback>(),
-                                                  float minProbability = 0.85);
+                                                  float minProbability = 0.3);
 
 }
 #endif // _OPENCV_ERFILTER_HPP_

modules/objdetect/src/erfilter.cpp

@@ -631,9 +631,10 @@ void ERFilterNM::er_merge(ERStat *parent, ERStat *child)
         child->probability = classifier->eval(*child);
     }
 
-    if ( ((classifier!=NULL)?(child->probability >= minProbability):true) &&
+    if ( (((classifier!=NULL)?(child->probability >= minProbability):true)||(nonMaxSuppression)) &&
          ((child->area >= (minArea*region_mask.rows*region_mask.cols)) &&
-          (child->area <= (maxArea*region_mask.rows*region_mask.cols))) )
+          (child->area <= (maxArea*region_mask.rows*region_mask.cols)) &&
+          (child->rect.width > 2) && (child->rect.height > 2)) )
     {
 
         num_accepted_regions++;
@@ -699,18 +700,24 @@ ERStat* ERFilterNM::er_save( ERStat *er, ERStat *parent, ERStat *prev )
 
     regions->back().parent = parent;
     if (prev != NULL)
+    {
       prev->next = &(regions->back());
+    }
     else if (parent != NULL)
       parent->child = &(regions->back());
 
     ERStat *old_prev = NULL;
     ERStat *this_er  = &regions->back();
 
+    if (this_er->parent == NULL)
+    {
+       this_er->probability = 0;
+    }
+
     if (nonMaxSuppression)
     {
         if (this_er->parent == NULL)
         {
-            this_er->probability = 0; //TODO this makes sense in order to select at least one region in short tree's but is it really necessary?
             this_er->max_probability_ancestor = this_er;
             this_er->min_probability_ancestor = this_er;
         }
@@ -722,15 +729,22 @@ ERStat* ERFilterNM::er_save( ERStat *er, ERStat *parent, ERStat *prev )
 
             if ( (this_er->max_probability_ancestor->probability > minProbability) && (this_er->max_probability_ancestor->probability - this_er->min_probability_ancestor->probability > minProbabilityDiff))
             {
+              this_er->max_probability_ancestor->local_maxima = true;
+              if ((this_er->max_probability_ancestor == this_er) && (this_er->parent->local_maxima))
+              {
+                this_er->parent->local_maxima = false;
+              }
+            }
+            else if (this_er->probability < this_er->parent->probability)
+            {
+              this_er->min_probability_ancestor = this_er;
+            }
+            else if (this_er->probability > this_er->parent->probability)
+            {
+              this_er->max_probability_ancestor = this_er;
+            }
 
-                this_er->max_probability_ancestor->local_maxima = true;
-                //TODO check here if the last local_maxima can be also suppressed, is the following correct?
-                //if (this_er->min_probability_ancestor->local_maxima)
-                //  this_er->min_probability_ancestor->local_maxima = false;
 
-                this_er->max_probability_ancestor = this_er;
-                this_er->min_probability_ancestor = this_er;
-            }
         }
     }
 
@@ -769,8 +783,7 @@ ERStat* ERFilterNM::er_tree_filter ( InputArray image, ERStat * stat, ERStat *pa
     findContours( region, contours, hierarchy, RETR_TREE, CHAIN_APPROX_NONE, Point(0, 0) );
     //TODO check epsilon parameter of approxPolyDP (set empirically) : we want more precission
     //     if the region is very small because otherwise we'll loose all the convexities
-    approxPolyDP( Mat(contours[0]), contour_poly, max(rect.width,rect.height)/25, true );
-
+    approxPolyDP( Mat(contours[0]), contour_poly, (float)min(rect.width,rect.height)/17, true );
 
     bool was_convex = false;
     int  num_inflexion_points = 0;
@@ -1120,7 +1133,6 @@ Ptr<ERFilter> createERFilterNM2(const Ptr<ERFilter::Callback>& cb, float minProb
 
     Ptr<ERFilterNM> filter = makePtr<ERFilterNM>();
 
-
     if (cb == NULL)
         filter->setCallback(makePtr<ERClassifierNM2>());
     else
@@ -1129,5 +1141,4 @@ Ptr<ERFilter> createERFilterNM2(const Ptr<ERFilter::Callback>& cb, float minProb
     filter->setMinProbability(minProbability);
     return (Ptr<ERFilter>)filter;
 }
-
 }