improvements to cnn face detection python interface (#780)

* improvements to cnn face detection interface

* mmod rectangle object renaming. possibility to set batch size in multi image detection. Added check to make sure images are all the same size.

dlib/image_processing/full_object_detection.h

@@ -140,6 +140,12 @@ namespace dlib
         bool ignore = false;
 
         operator rectangle() const { return rect; }
+        bool operator == (const mmod_rect& rhs) const
+        { 
+            return rect == rhs.rect 
+                   && detection_confidence == rhs.detection_confidence
+                   && ignore == rhs.ignore;
+        }
     };
 
     inline mmod_rect ignored_mmod_rect(const rectangle& r)

python_examples/cnn_face_detector.py

@@ -39,7 +39,6 @@
 #   Or downloaded from http://scikit-image.org/download.html.
 
 import sys
-
 import dlib
 from skimage import io
 
@@ -51,7 +50,7 @@ if len(sys.argv) < 3:
         "    http://dlib.net/files/mmod_human_face_detector.dat.bz2")
     exit()
 
-cnn_face_detection_model = dlib.cnn_face_detection_model_v1(sys.argv[1])
+cnn_face_detector = dlib.cnn_face_detection_model_v1(sys.argv[1])
 win = dlib.image_window()
 
 for f in sys.argv[2:]:
@@ -60,13 +59,27 @@ for f in sys.argv[2:]:
     # The 1 in the second argument indicates that we should upsample the image
     # 1 time.  This will make everything bigger and allow us to detect more
     # faces.
-    dets = cnn_face_detection_model.cnn_face_detector(img, 1)
+    dets = cnn_face_detector(img, 1)
+    '''
+    This detector returns a mmod_rectangles object. This object contains a list of mmod_rectangle objects.
+    These objects can be accessed by simply iterating over the mmod_rectangles object
+    The mmod_rectangle object has two member variables, a dlib.rectangle object, and a confidence score.
+    
+    It is also possible to pass a list of images to the detector.
+        - like this: dets = cnn_face_detector([image list], upsample_num, batch_size = 128)
+
+    In this case it will return a mmod_rectangless object.
+    This object behaves just like a list of lists and can be iterated over.
+    '''
     print("Number of faces detected: {}".format(len(dets)))
     for i, d in enumerate(dets):
-        print("Detection {}: Left: {} Top: {} Right: {} Bottom: {}".format(
-            i, d.left(), d.top(), d.right(), d.bottom()))
+        print("Detection {}: Left: {} Top: {} Right: {} Bottom: {} Confidence: {}".format(
+            i, d.rect.left(), d.rect.top(), d.rect.right(), d.rect.bottom(), d.confidence))
+
+    rects = dlib.rectangles()
+    rects.extend([d.rect for d in dets])
 
     win.clear_overlay()
     win.set_image(img)
-    win.add_overlay(dets)
-    dlib.hit_enter_to_continue()
+    win.add_overlay(rects)
+    dlib.hit_enter_to_continue()
\ No newline at end of file

tools/python/src/cnn_face_detector.cpp

@@ -2,10 +2,7 @@
 // License: Boost Software License   See LICENSE.txt for the full license.
 
 #include <dlib/python.h>
-#include <boost/shared_ptr.hpp>
 #include <dlib/matrix.h>
-#include <boost/python/slice.hpp>
-#include <dlib/geometry/vector.h>
 #include <dlib/dnn.h>
 #include <dlib/image_transforms.h>
 #include "indexing.h"
@@ -14,9 +11,6 @@ using namespace dlib;
 using namespace std;
 using namespace boost::python;
 
-typedef matrix<double,0,1> cv;
-
-
 class cnn_face_detection_model_v1
 {
 
@@ -27,13 +21,13 @@ public:
         deserialize(model_filename) >> net;
     }
 
-    std::vector<rectangle> cnn_face_detector (
+    std::vector<mmod_rect> detect (
         object pyimage,
         const int upsample_num_times
     )
     {
         pyramid_down<2> pyr;
-        std::vector<rectangle> rects;
+        std::vector<mmod_rect> rects;
 
         // Copy the data into dlib based objects
         matrix<rgb_pixel> image;
@@ -59,12 +53,69 @@ public:
         // if the image was upscaled.
         for (auto&& d : dets) {
             d.rect = pyr.rect_down(d.rect, upsample_num_times);
-            rects.push_back(d.rect);
+            rects.push_back(d);
         }
 
         return rects;
     }
 
+    std::vector<std::vector<mmod_rect> > detect_mult (
+        boost::python::list& imgs,
+        const int upsample_num_times,
+        const int batch_size = 128
+    )
+    {
+        pyramid_down<2> pyr;
+        std::vector<matrix<rgb_pixel> > dimgs;
+        dimgs.reserve(len(imgs));
+
+        for(int i = 0; i < len(imgs); i++)
+        {
+            // Copy the data into dlib based objects
+            matrix<rgb_pixel> image;
+            object tmp = boost::python::extract<object>(imgs[i]);
+            if (is_gray_python_image(tmp))
+                assign_image(image, numpy_gray_image(tmp));
+            else if (is_rgb_python_image(tmp))
+                assign_image(image, numpy_rgb_image(tmp));
+            else
+                throw dlib::error("Unsupported image type, must be 8bit gray or RGB image.");
+
+            for(int i = 0; i < upsample_num_times; i++)
+            {
+                pyramid_up(image);
+            }
+            dimgs.push_back(image);
+        }
+
+        for(int i = 1; i < dimgs.size(); i++)
+        {
+            if
+            (
+                dimgs[i - 1].nc() != dimgs[i].nc() ||
+                dimgs[i - 1].nr() != dimgs[i].nr()
+            )
+                throw dlib::error("Images in list must all have the same dimensions.");
+            
+        }        
+
+        auto dets = net(dimgs, batch_size);
+        std::vector<std::vector<mmod_rect> > all_rects;
+
+        for(auto&& im_dets : dets)
+        {
+            std::vector<mmod_rect> rects;
+            rects.reserve(im_dets.size());
+            for (auto&& d : im_dets) {
+                d.rect = pyr.rect_down(d.rect, upsample_num_times);
+                rects.push_back(d);
+            }
+            all_rects.push_back(rects);
+        }
+        
+        return all_rects;
+    }
+
 private:
 
     template <long num_filters, typename SUBNET> using con5d = con<num_filters,5,5,2,2,SUBNET>;
@@ -78,7 +129,6 @@ private:
     net_type net;
 };
 
-
 // ----------------------------------------------------------------------------------------
 
 void bind_cnn_face_detection()
@@ -86,10 +136,35 @@ void bind_cnn_face_detection()
     using boost::python::arg;
     {
     class_<cnn_face_detection_model_v1>("cnn_face_detection_model_v1", "This object detects human faces in an image.  The constructor loads the face detection model from a file. You can download a pre-trained model from http://dlib.net/files/mmod_human_face_detector.dat.bz2.", init<std::string>())
-        .def("cnn_face_detector", &cnn_face_detection_model_v1::cnn_face_detector, (arg("img"), arg("upsample_num_times")=0),
+        .def(
+            "__call__", 
+            &cnn_face_detection_model_v1::detect, 
+            (arg("img"), arg("upsample_num_times")=0),
             "Find faces in an image using a deep learning model.\n\
           - Upsamples the image upsample_num_times before running the face \n\
             detector."
+            )
+        .def(
+            "__call__", 
+            &cnn_face_detection_model_v1::detect_mult, 
+            (arg("imgs"), arg("upsample_num_times")=0, arg("batch_size")=128), 
+            "takes a list of images as input returning a 2d list of mmod rectangles"
             );
     }
+    {
+    typedef mmod_rect type;
+    class_<type>("mmod_rectangle", "Wrapper around a rectangle object and a detection confidence score.")
+        .def_readwrite("rect",   &type::rect)
+        .def_readwrite("confidence", &type::detection_confidence);
+    }
+    {
+    typedef std::vector<mmod_rect> type;
+    class_<type>("mmod_rectangles", "An array of mmod rectangle objects.")
+        .def(vector_indexing_suite<type>());
+    }
+    {
+    typedef std::vector<std::vector<mmod_rect> > type;
+    class_<type>("mmod_rectangless", "A 2D array of mmod rectangle objects.")
+        .def(vector_indexing_suite<type>());
+    } 
 }