Add mask method

rtengine/shmap.h

@@ -36,6 +36,7 @@ public:
     ~SHMap ();
 
     void update (Imagefloat* img, double radius, double lumi[3], bool hq, int skip);
+    void updateL (float** L, double radius, bool hq, int skip);
     void forceStat (float max_, float min_, float avg_);
 
 private:
@@ -43,6 +44,7 @@ private:
     bool multiThread;
 
     void fillLuminance( Imagefloat * img, float **luminance, double lumi[3] );
+    void fillLuminanceL( float ** L, float **luminance );
     void dirpyr_shmap(float ** data_fine, float ** data_coarse, int width, int height, LUTf & rangefn, int level, int scale);
 
 };