Fixed bug in evaluate_detectors() and added unit tests.

dlib/image_processing/scan_fhog_pyramid.h

@@ -1285,7 +1285,7 @@ namespace dlib
                 const double thresh = detectors[i].get_processed_w(d).w(scanner.get_num_dimensions());
 
                 impl::detect_from_fhog_pyramid<pyramid_type>(feats, scanner.get_feature_extractor(),
-                    detectors[i].get_processed_w(d).get_detect_argument(), thresh,
+                    detectors[i].get_processed_w(d).get_detect_argument(), thresh+adjust_threshold,
                     det_box_height, det_box_width, cell_size, max_filter_height,
                     max_filter_width, temp_dets);
 

dlib/test/object_detector.cpp

@@ -404,6 +404,22 @@ namespace
 
             validate_some_object_detector_stuff(images, detector, 1e-6);
         }
+
+        {
+            std::vector<object_detector<image_scanner_type> > detectors;
+            detectors.push_back(detector);
+            detectors.push_back(detector);
+            detectors.push_back(detector);
+
+            std::vector<rectangle> dets1 = evaluate_detectors(detectors, images[0]);
+            std::vector<rectangle> dets2 = detector(images[0]);
+            DLIB_TEST(dets1.size() > 0);
+            DLIB_TEST(dets2.size() == dets1.size());
+            for (unsigned long i = 0; i < dets1.size(); ++i)
+            {
+                DLIB_TEST(dets1[i] == dets2[i]);
+            }
+        }
     }
 
 // ----------------------------------------------------------------------------------------