diff --git a/rtengine/gauss.h b/rtengine/gauss.h
index 61e5e2fe4..5ee144a6a 100644
--- a/rtengine/gauss.h
+++ b/rtengine/gauss.h
@@ -23,7 +23,7 @@
 #include <cstring>
 #include <cmath>
 #include "opthelper.h"
-
+#include "stdio.h"
 // classical filtering if the support window is small:
 
 template<class T> void gaussHorizontal3 (T** src, T** dst, int W, int H, const float c0, const float c1)
@@ -765,22 +765,32 @@ template<class T> void gaussianBlur(T** src, T** dst, const int W, const int H,
 {
     double newSigma = sigma;
 
-    if(forceLowSigma) {
+    if(forceLowSigma && newSigma > 170.f) {
         newSigma /= sqrt(2.0);
 
         if(newSigma < 0.6) { // barrier to avoid using simple gauss version for higher radius
             newSigma = sigma;
             forceLowSigma = false;
+            gaussianBlur(src,dst,W,H,newSigma,forceLowSigma);
+        } else {
+            gaussianBlur(src,dst,W,H,newSigma,forceLowSigma);
+            gaussianBlur(dst,dst,W,H,newSigma,forceLowSigma);
         }
-    }
-
-    gaussHorizontal<T> (src, dst, W, H, newSigma);
-    gaussVertical<T>   (dst, dst, W, H, newSigma);
-
-    if(forceLowSigma) {
-        gaussHorizontal<T> (dst, dst, W, H, newSigma);
+    } else {
+        gaussHorizontal<T> (src, dst, W, H, newSigma);
         gaussVertical<T>   (dst, dst, W, H, newSigma);
+
     }
+//    #pragma omp critical
+//    printf("gauss sigma : %f / %f\n",sigma,newSigma);
+
+/*
+    if(forceLowSigma && newSigma > 170.f) {
+        gaussianBlur(dst,dst,W,H,newSigma,forceLowSigma);
+//        gaussHorizontal<T> (dst, dst, W, H, newSigma);
+//        gaussVertical<T>   (dst, dst, W, H, newSigma);
+    }
+*/
 }
 
 #endif
diff --git a/rtengine/ipretinex.cc b/rtengine/ipretinex.cc
index 54d6888ea..a7901fb71 100644
--- a/rtengine/ipretinex.cc
+++ b/rtengine/ipretinex.cc
@@ -44,6 +44,8 @@
 #include "rawimagesource.h"
 #include "improcfun.h"
 #include "opthelper.h"
+#include "StopWatch.h"
+
 #define MAX_RETINEX_SCALES   8
 #define clipretinex( val, minv, maxv )    (( val = (val < minv ? minv : val ) ) > maxv ? maxv : val )
 
@@ -98,6 +100,9 @@ void retinex_scales( float* scales, int nscales, int mode, int s, float high)
             }
         }
     }
+            for ( int i = 0; i < nscales; ++i )
+                printf("sigma[%d] : %f\n",i,scales[i]);
+
 }
 void mean_stddv2( float **dst, float &mean, float &stddv, int W_L, int H_L, float &maxtr, float &mintr)
 {
@@ -205,6 +210,7 @@ void mean_stddv( float **dst, float &mean, float &stddv, int W_L, int H_L, const
 
 void RawImageSource::MSR(float** luminance, float** originalLuminance, float **exLuminance,  int width, int height, RetinexParams deh, const RetinextransmissionCurve & dehatransmissionCurve, float &minCD, float &maxCD, float &mini, float &maxi, float &Tmean, float &Tsigma, float &Tmin, float &Tmax)
 {
+    StopWatch Stop1("MSR");
     if (deh.enabled) {//enabled
         float         mean, stddv, maxtr, mintr;
         //  float         mini, delta, maxi;