Merge branch 'sutr90-lab_pixel'

dlib/image_saver/save_png.h

@@ -80,9 +80,9 @@ namespace dlib
 
             impl::impl_save_png(file_name, row_pointers, img.nc(), impl::png_type_rgb_alpha, 8);
         }
-        else if (pixel_traits<pixel_type>::hsi || pixel_traits<pixel_type>::rgb)
+        else if (pixel_traits<pixel_type>::lab || pixel_traits<pixel_type>::hsi || pixel_traits<pixel_type>::rgb)
         {
-            // convert from HSI to RGB (Or potentially RGB pixels that aren't laid out as R G B)
+            // convert from Lab or HSI to RGB (Or potentially RGB pixels that aren't laid out as R G B)
             array2d<rgb_pixel> temp_img;
             assign_image(temp_img, img_);
             for (unsigned long i = 0; i < row_pointers.size(); ++i)

dlib/matrix/matrix_utilities.h

@@ -2573,7 +2573,8 @@ namespace dlib
             pixel_traits<P>::grayscale,
             pixel_traits<P>::rgb,
             pixel_traits<P>::hsi,
-            pixel_traits<P>::rgb_alpha
+            pixel_traits<P>::rgb_alpha,
+            pixel_traits<P>::lab
             >::value
         >
     struct pixel_to_vector_helper;
@@ -2637,6 +2638,21 @@ namespace dlib
         }
     };
 
+    template <typename P>
+    struct pixel_to_vector_helper<P,5>
+    {
+        template <typename M>
+        static void assign (
+                M& m,
+                const P& pixel
+        )
+        {
+            m(0) = static_cast<typename M::type>(pixel.l);
+            m(1) = static_cast<typename M::type>(pixel.a);
+            m(2) = static_cast<typename M::type>(pixel.b);
+        }
+    };
+
 
     template <
         typename T,
@@ -2660,7 +2676,8 @@ namespace dlib
             pixel_traits<P>::grayscale,
             pixel_traits<P>::rgb,
             pixel_traits<P>::hsi,
-            pixel_traits<P>::rgb_alpha
+            pixel_traits<P>::rgb_alpha,
+            pixel_traits<P>::lab
             >::value
         >
     struct vector_to_pixel_helper;
@@ -2724,6 +2741,21 @@ namespace dlib
         }
     };
 
+    template <typename P>
+    struct vector_to_pixel_helper<P,5>
+    {
+        template <typename M>
+        static void assign (
+                P& pixel,
+                const M& m
+        )
+        {
+            pixel.l = static_cast<unsigned char>(m(0));
+            pixel.a = static_cast<unsigned char>(m(1));
+            pixel.b = static_cast<unsigned char>(m(2));
+        }
+    };
+
     template <
         typename P,
         typename EXP