Made the test_box_overlap a little more flexible. This change breaks

backwards compatibility with the previous version though.

dlib/image_processing/box_overlap_testing.h

@@ -5,6 +5,7 @@
 
 #include "box_overlap_testing_abstract.h"
 #include "../geometry.h"
+#include <vector>
 
 namespace dlib
 {
@@ -15,17 +16,20 @@ namespace dlib
     {
     public:
         test_box_overlap (
-        ) : overlap_thresh(0.5)
+        ) : match_thresh(0.5), overlap_thresh(0.5)
         {}
 
         test_box_overlap (
+            double match_thresh_,
             double overlap_thresh_
-        ) : overlap_thresh(overlap_thresh_) 
+        ) : match_thresh(match_thresh_), overlap_thresh(overlap_thresh_) 
         {
             // make sure requires clause is not broken
-            DLIB_ASSERT(0 <= overlap_thresh && overlap_thresh <= 1, 
-                "\t test_box_overlap::test_box_overlap(overlap_thresh)"
+            DLIB_ASSERT(0 <= match_thresh && match_thresh <= 1  &&
+                        0 <= overlap_thresh && overlap_thresh <= 1,
+                "\t test_box_overlap::test_box_overlap(match_thresh, overlap_thresh)"
                 << "\n\t Invalid inputs were given to this function "
+                << "\n\t match_thresh:   " << match_thresh
                 << "\n\t overlap_thresh: " << overlap_thresh
                 << "\n\t this: " << this
                 );
@@ -39,7 +43,9 @@ namespace dlib
         {
             const double inner = a.intersect(b).area();
             const double outer = (a+b).area();
-            if (inner/outer > overlap_thresh)
+            if (inner/outer > match_thresh || 
+                inner/a.area() > overlap_thresh || 
+                inner/b.area() > overlap_thresh)
                 return true;
             else
                 return false;
@@ -51,7 +57,14 @@ namespace dlib
             return overlap_thresh;
         }
 
+        double get_match_thresh (
+        ) const
+        {
+            return match_thresh;
+        }
+
     private:
+        double match_thresh;
         double overlap_thresh;
     };
 
@@ -62,6 +75,7 @@ namespace dlib
         std::ostream& out
     )
     {
+        serialize(item.get_match_thresh(), out);
         serialize(item.get_overlap_thresh(), out);
     }
 
@@ -70,9 +84,44 @@ namespace dlib
         std::istream& in 
     )
     {
-        double overlap_thresh;
+        double overlap_thresh, match_thresh;
+        deserialize(match_thresh, in);
         deserialize(overlap_thresh, in);
-        item = test_box_overlap(overlap_thresh);
+        item = test_box_overlap(match_thresh, overlap_thresh);
+    }
+
+// ----------------------------------------------------------------------------------------
+
+    inline test_box_overlap find_tight_overlap_tester (
+        const std::vector<std::vector<rectangle> >& rects
+    )
+    {
+        double max_overlap = 0;
+        double max_match_score = 0;
+        for (unsigned long i = 0; i < rects.size(); ++i)
+        {
+            for (unsigned long j = 0; j < rects[i].size(); ++j)
+            {
+                for (unsigned long k = j+1; k < rects[i].size(); ++k)
+                {
+                    const rectangle a = rects[i][j];
+                    const rectangle b = rects[i][k];
+                    const double match_score = (a.intersect(b)).area()/(double)(a+b).area();
+                    const double overlap_a   = (a.intersect(b)).area()/(double)(a).area();
+                    const double overlap_b   = (a.intersect(b)).area()/(double)(b).area();
+
+                    if (match_score > max_match_score)
+                        max_match_score = match_score;
+
+                    if (overlap_a > max_overlap)
+                        max_overlap = overlap_a;
+                    if (overlap_b > max_overlap)
+                        max_overlap = overlap_b;
+                }
+            }
+        }
+
+        return test_box_overlap(max_match_score, max_overlap);
     }
 
 // ----------------------------------------------------------------------------------------

dlib/image_processing/box_overlap_testing_abstract.h

@@ -29,15 +29,19 @@ namespace dlib
         /*!
             ensures
                 - #get_overlap_thresh() == 0.5
+                - #get_match_thresh()   == 0.5
         !*/
 
         test_box_overlap (
+            double match_thresh,
             double overlap_thresh
         );
         /*!
             requires
+                - 0 <= match_thresh <= 1
                 - 0 <= overlap_thresh <= 1
             ensures
+                - #get_match_thresh() == match_thresh 
                 - #get_overlap_thresh() == overlap_thresh
         !*/
 
@@ -47,15 +51,31 @@ namespace dlib
         ) const;
         /*!
             ensures
-                - returns true if a.intersect(b).area()/(a+b).area > get_overlap_thresh()
-                  and false otherwise.  (i.e. returns true if a and b overlap enough)
+                - returns true if a and b overlap "enough". This is defined precisely below.
+                - if (a.intersect(b).area()/(a+b).area() > get_match_thresh() ||
+                      a.intersect(b).area()/a.area()     > get_overlap_thresh() ||
+                      a.intersect(b).area()/a.area()     > get_overlap_thresh() ) then
+                    - returns true
+                - else
+                    - returns false
         !*/
 
         double get_overlap_thresh (
         ) const;
         /*!
             ensures
-                - returns the threshold used to determine if two rectangles overlap.
+                - returns the threshold used to determine if two rectangles overlap.  This
+                  value is the percent of a rectangle's area covered by another rectangle.
+
+        !*/
+
+        double get_match_thresh (
+        ) const;
+        /*!
+            ensures
+                - returns the threshold used to determine if two rectangles match.
+                  Note that the match score varies from 0 to 1 and only becomes 1
+                  when two rectangles are identical.
 
         !*/
 
@@ -79,6 +99,24 @@ namespace dlib
         provides deserialization support
     !*/
 
+// ----------------------------------------------------------------------------------------
+
+    test_box_overlap find_tight_overlap_tester (
+        const std::vector<std::vector<rectangle> >& rects
+    );
+    /*!
+        ensures
+            - This function finds the most restrictive test_box_overlap object possible 
+              that is consistent with the given set of sets of rectangles.  
+            - To be precise, this function finds and returns a test_box_overlap object 
+              TBO such that:
+                - TBO.get_match_thresh() and TBO.get_overlap_thresh() are as small
+                  as possible such that the following conditions are satisfied.
+                - for all valid i:
+                    - for all distinct rectangles A and B in rects[i]:
+                        - TBO(A,B) == false
+    !*/
+
 // ----------------------------------------------------------------------------------------
 
 }