Changed from sum of squared differences to sum of abs differences

modules/photo/src/fast_nlmeans_denoising_invoker.hpp

@@ -130,13 +130,12 @@ FastNlMeansDenoisingInvoker<T, IT, UIT>::FastNlMeansDenoisingInvoker(
 
     const double WEIGHT_THRESHOLD = 0.001;
     const size_t ALLOC_CHUNK = 65536;
-    IT max_dist =
-        (IT)pixelInfo<T>::sampleMax() * (IT)pixelInfo<T>::sampleMax() * (IT)pixelInfo<T>::channels;
+    IT max_dist = (IT)pixelInfo<T>::sampleMax() * (IT)pixelInfo<T>::channels;
     size_t almost_max_dist = 0;
     while (true)
     {
         double dist = almost_max_dist * almost_dist2actual_dist_multiplier;
-        IT weight = (IT)round(fixed_point_mult_ * std::exp(-dist / (h * h * pixelInfo<T>::channels)));
+        IT weight = (IT)round(fixed_point_mult_ * std::exp(-dist*dist / (h * h * pixelInfo<T>::channels)));
         if (weight < WEIGHT_THRESHOLD * fixed_point_mult_ || dist > max_dist) break;
 
         if (almost_max_dist >= almost_dist2weight_.size())

modules/photo/src/fast_nlmeans_denoising_invoker_commons.hpp

@@ -85,7 +85,7 @@ template <typename T, typename IT> struct calcDist_
 {
     static inline IT f(const T a, const T b)
     {
-        return (IT)(a-b) * (IT)(a-b);
+        return std::abs((IT)(a-b));
     }
 };
 
@@ -93,7 +93,7 @@ template <typename ET, typename IT> struct calcDist_<Vec<ET, 2>, IT>
 {
     static inline IT f(const Vec<ET, 2> a, const Vec<ET, 2> b)
     {
-        return (IT)(a[0]-b[0])*(IT)(a[0]-b[0]) + (IT)(a[1]-b[1])*(IT)(a[1]-b[1]);
+        return std::abs((IT)(a[0]-b[0])) + std::abs((IT)(a[1]-b[1]));
     }
 };
 
@@ -101,10 +101,7 @@ template <typename ET, typename IT> struct calcDist_<Vec<ET, 3>, IT>
 {
     static inline IT f(const Vec<ET, 3> a, const Vec<ET, 3> b)
     {
-        return
-            (IT)(a[0]-b[0])*(IT)(a[0]-b[0]) +
-            (IT)(a[1]-b[1])*(IT)(a[1]-b[1]) +
-            (IT)(a[2]-b[2])*(IT)(a[2]-b[2]);
+        return std::abs((IT)(a[0]-b[0])) + std::abs((IT)(a[1]-b[1])) + std::abs((IT)(a[2]-b[2]));
     }
 };
 
@@ -121,31 +118,10 @@ static inline IT calcDist(const Mat& m, int i1, int j1, int i2, int j2)
     return calcDist<T, IT>(a,b);
 }
 
-template <typename T, typename IT> struct calcUpDownDist_
-{
-    static inline IT f(T a_up, T a_down, T b_up, T b_down)
-    {
-        IT A = a_down - b_down;
-        IT B = a_up - b_up;
-        return (A-B)*(A+B);
-    }
-};
-
-template <typename ET, int n, typename IT> struct calcUpDownDist_<Vec<ET, n>, IT>
-{
-private:
-    typedef Vec<ET, n> T;
-public:
-    static inline IT f(T a_up, T a_down, T b_up, T b_down)
-    {
-        return calcDist<T, IT>(a_down, b_down) - calcDist<T, IT>(a_up, b_up);
-    }
-};
-
 template <typename T, typename IT>
 static inline IT calcUpDownDist(T a_up, T a_down, T b_up, T b_down)
 {
-    return calcUpDownDist_<T, IT>::f(a_up, a_down, b_up, b_down);
+    return calcDist<T, IT>(a_down, b_down) - calcDist<T, IT>(a_up, b_up);
 };
 
 template <typename T, typename IT> struct incWithWeight_

modules/photo/src/fast_nlmeans_multi_denoising_invoker.hpp

@@ -141,13 +141,12 @@ FastNlMeansMultiDenoisingInvoker<T, IT, UIT>::FastNlMeansMultiDenoisingInvoker(
 
     const double WEIGHT_THRESHOLD = 0.001;
     const size_t ALLOC_CHUNK = 65536;
-    IT max_dist =
-        (IT)pixelInfo<T>::sampleMax() * (IT)pixelInfo<T>::sampleMax() * (IT)pixelInfo<T>::channels;
+    IT max_dist = (IT)pixelInfo<T>::sampleMax() * (IT)pixelInfo<T>::channels;
     size_t almost_max_dist = 0;
     while (true)
     {
         double dist = almost_max_dist * almost_dist2actual_dist_multiplier;
-        IT weight = (IT)round(fixed_point_mult_ * std::exp(-dist / (h * h * pixelInfo<T>::channels)));
+        IT weight = (IT)round(fixed_point_mult_ * std::exp(-dist*dist / (h * h * pixelInfo<T>::channels)));
         if (weight < WEIGHT_THRESHOLD * fixed_point_mult_ || dist > max_dist) break;
 
         if (almost_max_dist >= almost_dist2weight.size())