diff --git a/rtengine/improcfun.cc b/rtengine/improcfun.cc
index d24747751..30c476e14 100644
--- a/rtengine/improcfun.cc
+++ b/rtengine/improcfun.cc
@@ -75,14 +75,6 @@ namespace rtengine {
 #define kappa	903.29630 //24389.0/27.0;
 	
 	
-//%%%%%%%%%%%%
-#define epsilon 0.00885645 //216/24389
-#define kappainv 0.00110706 //inverse of kappa
-#define kapeps 8 // kappa*epsilon
-#define f2xyz(f) (( (g=f*f*f) > epsilon) ? g : (116*f-16)*kappainv)
-//%%%%%%%%%%%%
-
-
 extern const Settings* settings;
 
 LUTf ImProcFunctions::cachef ;
diff --git a/rtengine/improcfun.h b/rtengine/improcfun.h
index 84d4964cf..311b7f45d 100644
--- a/rtengine/improcfun.h
+++ b/rtengine/improcfun.h
@@ -132,6 +132,13 @@ class ImProcFunctions {
 
 	//void gamutmap(LabImage* );
 	void gamutmap(float &X, float &Y, float &Z, const double p[3][3]);
+
+    static inline float f2xyz(register float f) {
+        const float epsilonExpInv3 = 6.0/29.0;
+        const float kappaInv = 27.0/24389.0;  // inverse of kappa
+
+        return (f > epsilonExpInv3) ? f*f*f : (116 * f - 16) * kappaInv;
+    }
 };
 }
 #endif
diff --git a/rtengine/iplab2rgb.cc b/rtengine/iplab2rgb.cc
index 46f4ddea2..65c5f9ade 100644
--- a/rtengine/iplab2rgb.cc
+++ b/rtengine/iplab2rgb.cc
@@ -39,11 +39,6 @@ namespace rtengine {
 #define CLIPTO(a,b,c) ((a)>(b)?((a)<(c)?(a):(c)):(b))
 #define CLIP01(a) ((a)>0?((a)<1?(a):1):0)
 	
-#define epsilon 0.00885645 //216/24389
-#define kappa 903.2963 //24389/27
-#define kappainv 0.00110706 //inverse of kappa
-#define kapeps 8 // kappa*epsilon
-#define Lab2xyz(f) (( (g=f*f*f) > epsilon) ? g : (116*f-16)*kappainv)
 	
 #define D50x 0.96422
 #define D50z 0.82521
@@ -83,9 +78,9 @@ void ImProcFunctions::lab2rgb (LabImage* lab, Image8* image) {
 				fx = (0.002 * ra[j]) / 327.68 + fy;
 				fz = fy - (0.005 * rb[j]) / 327.68;
 				
-				x_ = Lab2xyz(fx)*D50x;//should this be 32767???  buffer is short int !!!
-				y_ = Lab2xyz(fy);
-				z_ = Lab2xyz(fz)*D50z;
+				x_ = f2xyz(fx)*D50x;//should this be 32767???  buffer is short int !!!
+				y_ = f2xyz(fy);
+				z_ = f2xyz(fz)*D50z;
 
                 buffer[iy++] = CLIP01(x_);
                 buffer[iy++] = CLIP01(y_);
@@ -118,9 +113,9 @@ void ImProcFunctions::lab2rgb (LabImage* lab, Image8* image) {
 				fx = (0.002 * ra[j]) / 327.68 + fy;
 				fz = fy - (0.005 * rb[j]) / 327.68;
 				
-				x_ = 65535.0*Lab2xyz(fx)*D50x;
-				y_ = 65535.0*Lab2xyz(fy);
-				z_ = 65535.0*Lab2xyz(fz)*D50z;
+				x_ = 65535.0 * f2xyz(fx)*D50x;
+				y_ = 65535.0 * f2xyz(fy);
+				z_ = 65535.0 * f2xyz(fz)*D50z;
 
 				xyz2srgb(x_,y_,z_,R,G,B);
 
@@ -175,9 +170,9 @@ Image8* ImProcFunctions::lab2rgb (LabImage* lab, int cx, int cy, int cw, int ch,
 				float fx = (0.002 * ra[j])/327.68 + fy;
 				float fz = fy - (0.005 * rb[j])/327.68;
 				
-				float x_ = 65535.0*Lab2xyz(fx)*D50x;
-				float y_ = 65535.0*Lab2xyz(fy);
-				float z_ = 65535.0*Lab2xyz(fz)*D50z;
+				float x_ = 65535.0 * f2xyz(fx)*D50x;
+				float y_ = 65535.0 * f2xyz(fy);
+				float z_ = 65535.0 * f2xyz(fz)*D50z;
 
                 buffer[iy++] = CLIP((int)x_);
                 buffer[iy++] = CLIP((int)y_);
@@ -218,9 +213,9 @@ Image8* ImProcFunctions::lab2rgb (LabImage* lab, int cx, int cy, int cw, int ch,
 				float fx = (0.002 * ra[j])/327.68 + fy;
 				float fz = fy - (0.005 * rb[j])/327.68;
 				
-				float x_ = 65535.0*Lab2xyz(fx)*D50x;
-				float y_ = 65535.0*Lab2xyz(fy);
-				float z_ = 65535.0*Lab2xyz(fz)*D50z;
+				float x_ = 65535.0 * f2xyz(fx)*D50x;
+				float y_ = 65535.0 * f2xyz(fy);
+				float z_ = 65535.0 * f2xyz(fz)*D50z;
 
 				xyz2rgb(x_,y_,z_,R,G,B,rgb_xyz);
 
@@ -262,9 +257,9 @@ Image16* ImProcFunctions::lab2rgb16 (LabImage* lab, int cx, int cy, int cw, int
 				float fx = (0.002 * ra[j])/327.68 + fy;
 				float fz = fy - (0.005 * rb[j])/327.68;
 				
-				float x_ = 65535.0*Lab2xyz(fx)*D50x;
-				float y_ = 65535.0*Lab2xyz(fy);
-				float z_ = 65535.0*Lab2xyz(fz)*D50z;
+				float x_ = 65535.0 * f2xyz(fx)*D50x;
+				float y_ = 65535.0 * f2xyz(fy);
+				float z_ = 65535.0 * f2xyz(fz)*D50z;
 
 				xa[j-cx] = CLIP((int)x_);
 				ya[j-cx] = CLIP((int)y_);
@@ -293,9 +288,9 @@ Image16* ImProcFunctions::lab2rgb16 (LabImage* lab, int cx, int cy, int cw, int
 				float fx = (0.002 * ra[j])/327.68 + fy;
 				float fz = fy - (0.005 * rb[j])/327.68;
 				
-				float x_ = 65535.0*Lab2xyz(fx)*D50x;
-				float y_ = 65535.0*Lab2xyz(fy);
-				float z_ = 65535.0*Lab2xyz(fz)*D50z;
+				float x_ = 65535.0 * f2xyz(fx)*D50x;
+				float y_ = 65535.0 * f2xyz(fy);
+				float z_ = 65535.0 * f2xyz(fz)*D50z;
 
 				xyz2srgb(x_,y_,z_,R,G,B);
 
diff --git a/rtengine/rawimagesource.cc b/rtengine/rawimagesource.cc
index 8bdc9b6e1..3ab67cd81 100644
--- a/rtengine/rawimagesource.cc
+++ b/rtengine/rawimagesource.cc
@@ -68,13 +68,6 @@ PIX_SORT(p[4],p[7]); PIX_SORT(p[4],p[2]); PIX_SORT(p[6],p[4]); \
 PIX_SORT(p[4],p[2]); median=p[4];} //a4 is the median
 	
 	
-//%%%%%%%%%%%%
-#define epsilon 0.00885645 //216/24389
-#define kappainv 0.00110706 //inverse of kappa
-#define kapeps 8 // kappa*epsilon
-#define f2xyz(f) (( (g=f*f*f) > epsilon) ? g : (116*f-16)*kappainv)
-//%%%%%%%%%%%%
-	
 
 RawImageSource::RawImageSource ()
 :ImageSource()
@@ -1824,11 +1817,10 @@ void RawImageSource::HLRecovery_CIELab (float* rin, float* gin, float* bin, floa
             // convert back to rgb
             double fz = fy - y + z;
             double fx = fy + x - y;
-			// again shouldn't this be a universal, centrally defined function???
-			double zr = f2xyz(fz);
-            double xr = f2xyz(fx);
-            //double zr = (fz<=0.206893) ? ((116.0*fz-16.0)/903.3) : (fz * fz * fz);
-            //double xr = (fx<=0.206893) ? ((116.0*fx-16.0)/903.3) : (fx * fx * fx);
+
+			double zr = ImProcFunctions::f2xyz(fz);
+            double xr = ImProcFunctions::f2xyz(fx);
+
             x = xr*65535.0 ;
             y = yy;
             z = zr*65535.0 ;