Make the mmod loss not spam messages in the unit tests

dlib/dnn/loss.h

@@ -941,6 +941,9 @@ namespace dlib
         test_box_overlap overlaps_ignore;
         bool use_bounding_box_regression = false; 
         double bbr_lambda = 100; 
+        // This field is intentionally not serialized because I want people to really think hard
+        // about ignoring the warnings that this suppresses.
+        bool be_quiet = false;
 
         use_image_pyramid assume_image_pyramid = use_image_pyramid::yes;
 
@@ -1431,11 +1434,14 @@ namespace dlib
                         const size_t idx = (k*output_tensor.nr() + p.y())*output_tensor.nc() + p.x();
                         const auto i = idx_to_truth_rect.find(idx);
                         if (i != idx_to_truth_rect.end())
+                        {
+                            if (!options.be_quiet) 
                             {
                                 // Ignore duplicate truth box in feature coordinates.
                                 std::cout << "Warning, ignoring object.  We encountered a truth rectangle located at " << x.rect;
                                 std::cout << ", and we are ignoring it because it maps to the exact same feature coordinates ";
                                 std::cout << "as another truth rectangle located at " << i->second << "." << std::endl;
+                            }
 
                             loss -= options.loss_per_missed_target;
                             truth_idxs.push_back(-1);
@@ -1515,6 +1521,8 @@ namespace dlib
                                 // added for it in the code above.
                                 loss -= options.loss_per_missed_target-out_data[idx];
                                 g[idx] = 0;
+                                if (!options.be_quiet) 
+                                {
                                     std::cout << "Warning, ignoring object.  We encountered a truth rectangle located at " << (*truth)[i].rect;
                                     std::cout << " that is suppressed by non-max-suppression ";
                                     std::cout << "because it is overlapped by another truth rectangle located at " << best_matching_truth_box 
@@ -1524,6 +1532,7 @@ namespace dlib
                             }
                         }
                     }
+                }
 
                 hit_truth_table.assign(hit_truth_table.size(), false);
                 final_dets.clear();

dlib/dnn/loss_abstract.h

@@ -861,6 +861,11 @@ namespace dlib
         // getting the bounding box shape correct.
         double bbr_lambda = 100; 
 
+        // Tell the loss not to print warnings about impossible labels.  You should think very hard
+        // before turning this off as it's very often telling you something is really wrong with
+        // your training data.
+        bool be_quiet = false;
+
         mmod_options (
             const std::vector<std::vector<mmod_rect>>& boxes,
             const unsigned long target_size,      

dlib/test/dnn.cpp

@@ -4006,6 +4006,7 @@ namespace
         const std::vector<mmod_rect> labels = generate_labels();
 
         mmod_options options(use_image_pyramid::no, { labels });
+        options.be_quiet = true;
 
         // Define a simple network.
         using net_type = loss_mmod<con<1,5,5,1,1,con<1,5,5,2,2,input<input_image_type>>>>;