diff --git a/dlib/gui_widgets/base_widgets.h b/dlib/gui_widgets/base_widgets.h
index 76619338e..e8c88216c 100644
--- a/dlib/gui_widgets/base_widgets.h
+++ b/dlib/gui_widgets/base_widgets.h
@@ -410,8 +410,8 @@ namespace dlib
             auto_mutex M(m);
             assign_image_scaled(img,new_img);
             rectangle old(rect);
-            rect.set_right(rect.left()+img.nc()-1); 
-            rect.set_bottom(rect.top()+img.nr()-1);
+            rect.set_right(rect.left()+num_columns(img)-1); 
+            rect.set_bottom(rect.top()+num_rows(img)-1);
             parent.invalidate_rectangle(rect+old);
         }
 
diff --git a/dlib/gui_widgets/canvas_drawing.h b/dlib/gui_widgets/canvas_drawing.h
index 1a077d42e..61f688112 100644
--- a/dlib/gui_widgets/canvas_drawing.h
+++ b/dlib/gui_widgets/canvas_drawing.h
@@ -681,7 +681,7 @@ namespace dlib
     {
         const long x = p.x();
         const long y = p.y();
-        rectangle rect(x,y,img.nc()+x-1,img.nr()+y-1);
+        rectangle rect(x,y,num_columns(img)+x-1,num_rows(img)+y-1);
         rectangle area = c.intersect(rect).intersect(area_);
         if (area.is_empty())
             return;
@@ -709,11 +709,11 @@ namespace dlib
     )
     {
         const rectangle area = c.intersect(rect).intersect(area_);
-        if (area.is_empty() || img.size() == 0)
+        if (area.is_empty() || num_columns(img) * num_rows(img) == 0)
             return;
 
-        const matrix<long,1> x = matrix_cast<long>(round(linspace(0, img.nc()-1, rect.width())));
-        const matrix<long,1> y = matrix_cast<long>(round(linspace(0, img.nr()-1, rect.height())));
+        const matrix<long,1> x = matrix_cast<long>(round(linspace(0, num_columns(img)-1, rect.width())));
+        const matrix<long,1> y = matrix_cast<long>(round(linspace(0, num_rows(img)-1, rect.height())));
 
         for (long row = area.top(); row <= area.bottom(); ++row)
         {
diff --git a/examples/dnn_mmod_find_cars2_ex.cpp b/examples/dnn_mmod_find_cars2_ex.cpp
index 65a919e11..b9fffbba0 100644
--- a/examples/dnn_mmod_find_cars2_ex.cpp
+++ b/examples/dnn_mmod_find_cars2_ex.cpp
@@ -27,7 +27,7 @@ using namespace dlib;
 
 
 
-// The rear view vehicle detector network
+// The front and rear view vehicle detector network
 template <long num_filters, typename SUBNET> using con5d = con<num_filters,5,5,2,2,SUBNET>;
 template <long num_filters, typename SUBNET> using con5  = con<num_filters,5,5,1,1,SUBNET>;
 template <typename SUBNET> using downsampler  = relu<affine<con5d<32, relu<affine<con5d<32, relu<affine<con5d<16,SUBNET>>>>>>>>>;