diff --git a/rtengine/curves.cc b/rtengine/curves.cc
index 5a5b93d2a..df2696fff 100644
--- a/rtengine/curves.cc
+++ b/rtengine/curves.cc
@@ -622,47 +622,6 @@ void CurveFactory::complexCurve (double ecomp, double black, double hlcompr, dou
 		
 		//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 		// tone curve base. a: slope (from exp.comp.), b: black, def_mul: max. x value (can be>1), hr,sr: highlight,shadow recovery
-		/*
-		 std::vector<double> basecurvePoints;
-		 basecurvePoints.push_back((double)((CurveType)NURBS));
-		 float blackx = MIN(1,black/(a*def_mul));
-		 float whitex = 1/(a*def_mul);//point in x at which line of slope a*def_mul starting at (0,0) reaches y=1
-		 float toneslope=(1-0)/(shoulderx-toex);
-		 toey = 0.01 + 0.3*(MAX(0,shcompr/100.0-0.25));
-		 toex = blackx + toey/toneslope;
-		 if (whitex<1) {//a>1; positive EC
-		 //move shoulder down if there is highlight rolloff
-		 shouldery = 1-(0.3)*(MAX(0,hlcompr/100.0-0.25));
-		 shoulderx = whitex - (1-shouldery)/toneslope;
-		 } else {//a<1; negative EC
-		 //if (shoulderx>1) {
-		 shoulderx = 1;
-		 shouldery = a*def_mul;
-		 }
-		 
-		 basecurvePoints.push_back(MAX(0,blackx*(1-shcompr/25.0))); //black point.  Value in [0 ; 1] range
-		 basecurvePoints.push_back(0); //black point.  Value in [0 ; 1] range
-		 
-		 basecurvePoints.push_back(toex); //toe point
-		 basecurvePoints.push_back(toey); //value at toe point
-		 
-		 if (toex<1) {
-		 //add a point along the line between the toe point and shoulder point
-		 basecurvePoints.push_back(0.4*toex+0.6*shoulderx); //mid point
-		 basecurvePoints.push_back(0.4*toey+0.6*shouldery); //value at mid point
-		 
-		 basecurvePoints.push_back(shoulderx); //shoulder point
-		 basecurvePoints.push_back(shouldery); //value at shoulder point
-		 if (shoulderx<1) {
-		 basecurvePoints.push_back(MIN(0.99,whitex+0.01+(1-whitex-0.01)*(hlcompr/70.0)); // lead into white point
-		 basecurvePoints.push_back(1); // value near white point
-		 basecurvePoints.push_back(1); // white point
-		 basecurvePoints.push_back(1); // value at white point
-		 }
-		 }
-		 Curve* basecurve = NULL;
-		 basecurve = new Curve (basecurvePoints, CURVES_MIN_POLY_POINTS/skip); // Actually, CURVES_MIN_POLY_POINTS = 1000,
-		 */
 		//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 		
 		std::vector<double> brightcurvePoints;
@@ -702,7 +661,6 @@ void CurveFactory::complexCurve (double ecomp, double black, double hlcompr, dou
 			// apply base curve, thus, exposure compensation and black point with shadow and highlight protection
 			val = basecurve (val*def_mul, a, 0, def_mul, hlcompr/100.0, 0);
 			//val = basecurve (val*def_mul, a, black, def_mul, hlcompr/100.0, 1.5*shcompr/100.0);
-			//val = basecurvenew->getVal (val);
 			
 			hlCurve[i] = (65535.0 * CLIPD(val));
 			
@@ -710,7 +668,7 @@ void CurveFactory::complexCurve (double ecomp, double black, double hlcompr, dou
 			// change to [0,1] range
 			val = (double)i / 65535.0;
 			
-			val = basecurve (val, 1, black, def_mul, 1, 1.5*shcompr/100.0);
+			val = basecurve (val, 1, black, 1, 0, 1.5*shcompr/100.0);
 			
 			shCurve[i] = (65535.0 * CLIPD(val));
 		}
@@ -721,7 +679,6 @@ void CurveFactory::complexCurve (double ecomp, double black, double hlcompr, dou
 			// change to [0,1] range
 			double val = (double)i / 65535.0;
 			float val0 = val;
-			float cum = (int)shCurve[(int)(hlCurve[i])];
 			
 			// gamma correction
 			if (gamma_>0) 
@@ -751,8 +708,6 @@ void CurveFactory::complexCurve (double ecomp, double black, double hlcompr, dou
 			dcurve[i] = CLIPD(val);
 		}
 		delete tcurve;
-		
-		//delete basecurvenew; // ...when you don't need it anymore
 		delete brightcurve; 
 		
 		// if skip>1, let apply linear interpolation in the skipped points of the curve
diff --git a/rtengine/curves.h b/rtengine/curves.h
index c9bad3d37..0330863e4 100644
--- a/rtengine/curves.h
+++ b/rtengine/curves.h
@@ -103,13 +103,13 @@ class CurveFactory {
 			else 
 				return y*clower2(x/m, slope*m/y, 2.0-sr);
 		} else {
-			double m = a>1 ? b+0.25*(1-b)/a : b+(1-b)/4;
-			double y = a>1 ? 0.25 : 0.25*a;
 			double slope = a/(1-b);
+			double m = a*D>1 ? b/a+(0.25+0.75*(1-1/D))/slope : b+(1-b)/4;
+			double y = a*D>1 ? 0.25 : (m-b/a)*slope;
 			if (x<=m)
-				return b==0 ? x*a : clower (x/m, slope*m/y, sr) * y;
-			else if (a>1)
-				return y+(1.0-y)*cupper2((x-m)/(1-m), slope*(1-m)/(1.0-y), hr);
+				return b==0 ? x*slope : clower (x/m, slope*m/y, sr) * y;
+			else if (a*D>1)
+				return y+(1.0-y)*cupper2((x-m)/(D-m), slope*(D-m)/(1.0-y), hr);
 			else
 				return y+(x-m)*slope;
 		}
diff --git a/rtengine/improccoordinator.cc b/rtengine/improccoordinator.cc
index 9483955e5..7664ffb7c 100644
--- a/rtengine/improccoordinator.cc
+++ b/rtengine/improccoordinator.cc
@@ -375,10 +375,15 @@ void ImProcCoordinator::updateHistograms (int x1, int y1, int x2, int y2) {
     memset (rhist, 0, 256*sizeof(int));
     memset (ghist, 0, 256*sizeof(int));
     memset (bhist, 0, 256*sizeof(int));
+	
+	memset (bcrgbhist, 0, 256*sizeof(int));
+	memset (bcLhist, 0, 256*sizeof(int));
 
     for (int i=y1; i<y2; i++) {
         int ofs = (i*pW + x1)*3;
         for (int j=x1; j<x2; j++) {
+			int Y = CLIPTO((299*previmg->data[ofs]+587*previmg->data[ofs+1]+114*previmg->data[ofs+2]),0,255000)/1000;
+			bcrgbhist[Y]++;
             rhist[previmg->data[ofs++]]++;
             ghist[previmg->data[ofs++]]++;
             bhist[previmg->data[ofs++]]++;
@@ -387,8 +392,10 @@ void ImProcCoordinator::updateHistograms (int x1, int y1, int x2, int y2) {
 
     memset (Lhist, 0, 256*sizeof(int));
     for (int i=y1; i<y2; i++)
-        for (int j=x1; j<x2; j++) 
+        for (int j=x1; j<x2; j++) {
             Lhist[nprevl->L[i][j]/256]++;
+			bcLhist[nprevl->L[i][j]/256]++;
+		}
 	
 	/*for (int i=0; i<256; i++) {
 		Lhist[i] = (int)(256*sqrt(Lhist[i]));