diff --git a/rtengine/CA_correct_RT.cc b/rtengine/CA_correct_RT.cc
index bcd6ebfb9..4cc9151ea 100644
--- a/rtengine/CA_correct_RT.cc
+++ b/rtengine/CA_correct_RT.cc
@@ -390,8 +390,8 @@ void RawImageSource::CA_correct_RT() {
 			
 			// along line segments, find the point along each segment that minimizes the color variance
 			// averaged over the tile; evaluate for up/down and left/right away from R/B grid point 
-			for (rr=8; rr < rr1-8; rr++)
-				for (cc=8+(FC(rr,2)&1), indx=rr*TS+cc, c = FC(rr,cc); cc < cc1-8; cc+=2, indx+=2) {
+			for (rr=rrmin+8; rr < rrmax-8; rr++)
+				for (cc=ccmin+8+(FC(rr,2)&1), indx=rr*TS+cc, c = FC(rr,cc); cc < ccmax-8; cc+=2, indx+=2) {
 					
 					if (rgb[indx][c]>0.8*clip_pt || Gtmp[indx]>0.8*clip_pt) continue;
 
@@ -430,7 +430,9 @@ void RawImageSource::CA_correct_RT() {
 			for (c=0; c<3; c+=2){
 				for (j=0; j<2; j++) {// vert/hor
 					//printf("hblock %d vblock %d j %d c %d areawt %d \n",hblock,vblock,j,c,areawt[j][c]);
-					if (areawt[j][c]>500) {
+					//printf("hblock %d vblock %d j %d c %d areawt %d ",hblock,vblock,j,c,areawt[j][c]);
+
+					if (areawt[j][c]>0) {
 						CAshift[j][c]=coeff[j][1][c]/coeff[j][2][c];
 						blockwt[vblock*hblsz+hblock]= areawt[j][c];//*coeff[j][2][c]/(eps+coeff[j][0][c]) ;
 					} else {
@@ -438,6 +440,8 @@ void RawImageSource::CA_correct_RT() {
 						blockwt[vblock*hblsz+hblock]=0;
 					}
 					
+					//printf("%f  \n",CAshift[j][c]);
+
 					//CAshift[j][c]=coeff[j][1][c]/coeff[j][2][c];
 					//blockwt[vblock*hblsz+hblock] = (float)(rr1-8)*(cc1-8)/4 * coeff[j][2][c]/(eps+coeff[j][0][c]) ;
 					
@@ -489,7 +493,7 @@ void RawImageSource::CA_correct_RT() {
 			}
 		}
 	
-	//if (verbose) fprintf (stderr,_("tile variances %f %f %f %f \n"),blockvar[0][0],blockvar[1][0],blockvar[0][2],blockvar[1][2] );
+	//printf ("tile variances %f %f %f %f \n",blockvar[0][0],blockvar[1][0],blockvar[0][2],blockvar[1][2] );
 	
 	
 	// %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
diff --git a/rtengine/impulse_denoise.h b/rtengine/impulse_denoise.h
index ed9d226fb..f1bb9bf3c 100644
--- a/rtengine/impulse_denoise.h
+++ b/rtengine/impulse_denoise.h
@@ -24,15 +24,17 @@
 #include <algorithm>
 
 // %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-// Gabor's implementation of bilateral filtering, without input pixel
+// modified version of Gabor's implementation of bilateral filtering, without input pixel
 
 #define NBRWT(a,b) (src[i - a][j - b] * ec[src[i - a][j - b]-src[i][j]+0x10000])
-#define NORM(a,b) (1 + ec[src[i - a][j - b]-src[i][j]+0x10000])
+#define NORM(a,b) (ec[src[i - a][j - b]-src[i][j]+0x10000])
+
+//ec[i] = (int)(exp(-(double)(i-0x10000)*(double)(i-0x10000) / (2.0*rangewidth*rangewidth))*scale); \
 
 #define RB_BEGIN(a,b)   double scale = (a); \
 	int* ec = new int [0x20000]; \
 	for (int i=0; i<0x20000; i++) \
-	ec[i] = (int)(exp(-(double)(i-0x10000)*(double)(i-0x10000) / (2.0*rangewidth*rangewidth))*scale); \
+	ec[i] = (int)(1 + 1024/(abs(i-0x10000) + 1)); \
 	int rstart = b; \
 	int rend = H-b; \
 	int cstart = b; \
@@ -97,7 +99,7 @@ template<class T> void impulse_nr (T** src, T** dst, int width, int height, doub
 	//The cleaning algorithm starts here
 	
 	//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-	// modified bilateral filter for lowpass image, omitting input pixel
+	// modified bilateral filter for lowpass image, omitting input pixel; or Gaussian blur
 	
 	static float eps = 1.0;
 	float wtdsum, dirwt, norm;
@@ -127,7 +129,7 @@ template<class T> void impulse_nr (T** src, T** dst, int width, int height, doub
 			hfnbrave = (hfnbrave-hpfabs)/24;
 			hpfabs>(hfnbrave*(5.5-thresh)) ? impish[i][j]=1 : impish[i][j]=0;
 			
-		}//now impulsive values have been corrected
+		}//now impulsive values have been identified
 	
 	for (int i=0; i < height; i++)
 		for (int j=0; j < width; j++) {