gistfile1.txt

diff --git a/rtengine/FTblockDN.cc b/rtengine/FTblockDN.cc
index 6bb0c4c..efe9769 100644
--- a/rtengine/FTblockDN.cc
+++ b/rtengine/FTblockDN.cc
@@ -2102,13 +2102,13 @@ float ImProcFunctions::MadMax(float * DataList, int & max, int datalen)
 
 }
 
-float ImProcFunctions::Mad(float * DataList, const int datalen)
+float ImProcFunctions::Mad(float * DataList, int datalen)
 {
     if(datalen <= 1) { // Avoid possible buffer underrun
         return 0;
     }
 
-    //computes Median Absolute Deviation
+    //computes Median
     //DataList values should mostly have abs val < 256 because we are in Lab mode
     int histo[256] ALIGNED64 = {0};
 
@@ -2117,8 +2117,9 @@ float ImProcFunctions::Mad(float * DataList, const int datalen)
         histo[min(255, abs(static_cast<int>(DataList[i])))]++;
     }
 
-    //find median of histogram
-    int median = 0, count = 0;
+    //find median of histogram, but skip first 2 values
+    int median = 2, count = 0;
+    datalen -= (histo[0] + histo[1]);
 
     while (count < datalen / 2) {
         count += histo[median];
diff --git a/rtengine/improcfun.h b/rtengine/improcfun.h
index 7ea7bbe..3fb4d2e 100644
--- a/rtengine/improcfun.h
+++ b/rtengine/improcfun.h
@@ -324,7 +324,7 @@ public:
     void Noise_residualAB(wavelet_decomposition &WaveletCoeffs_ab, float &chresid, float &chmaxresid, bool denoiseMethodRgb);
     void calcautodn_info (float &chaut, float &delta, int Nb, int levaut, float maxmax, float lumema, float chromina, int mode, int lissage, float redyel, float skinc, float nsknc);
     float MadMax(float * DataList, int &max, int datalen);
-    float Mad(float * DataList, const int datalen);
+    float Mad(float * DataList, int datalen);
     float MadRgb(float * DataList, const int datalen);
 
     // pyramid wavelet