From 2dd28ac0fe436c156e87bbf2369588de1d07fca3 Mon Sep 17 00:00:00 2001
From: Davis King <davis@dlib.net>
Date: Mon, 30 May 2011 10:51:20 -0400
Subject: [PATCH] Changed hysteresis_threshold() so it properly handles signed
 pixel types.

---
 dlib/image_transforms/thresholding.h          | 5 ++---
 dlib/image_transforms/thresholding_abstract.h | 4 ++--
 2 files changed, 4 insertions(+), 5 deletions(-)

diff --git a/dlib/image_transforms/thresholding.h b/dlib/image_transforms/thresholding.h
index 9ede03da0..509f59d12 100644
--- a/dlib/image_transforms/thresholding.h
+++ b/dlib/image_transforms/thresholding.h
@@ -173,8 +173,8 @@ namespace dlib
     void hysteresis_threshold (
         const in_image_type& in_img,
         out_image_type& out_img,
-        unsigned long lower_thresh,
-        unsigned long upper_thresh
+        typename pixel_traits<typename in_image_type::type>::basic_pixel_type lower_thresh,
+        typename pixel_traits<typename in_image_type::type>::basic_pixel_type upper_thresh
     )
     {
         COMPILE_TIME_ASSERT( pixel_traits<typename in_image_type::type>::has_alpha == false );
@@ -198,7 +198,6 @@ namespace dlib
         }
 
         out_img.set_size(in_img.nr(),in_img.nc());
-        assign_all_pixels(out_img,0);
 
         const long size = 50;
         long rstack[size];
diff --git a/dlib/image_transforms/thresholding_abstract.h b/dlib/image_transforms/thresholding_abstract.h
index a61fc6277..30e7269b9 100644
--- a/dlib/image_transforms/thresholding_abstract.h
+++ b/dlib/image_transforms/thresholding_abstract.h
@@ -78,8 +78,8 @@ namespace dlib
     void hysteresis_threshold (
         const in_image_type& in_img,
         out_image_type& out_img,
-        unsigned long lower_thresh,
-        unsigned long upper_thresh
+        typename pixel_traits<typename in_image_type::type>::basic_pixel_type lower_thresh,
+        typename pixel_traits<typename in_image_type::type>::basic_pixel_type upper_thresh
     );
     /*!
         requires