diff --git a/rtengine/iplocallab.cc b/rtengine/iplocallab.cc
index ee7436be4..8743ea08b 100644
--- a/rtengine/iplocallab.cc
+++ b/rtengine/iplocallab.cc
@@ -2827,7 +2827,7 @@ static void mean_fab(int begx, int begy, int cx, int cy, int xEn, int yEn, LabIm
     fab = meanfab + multsigma * stddv;
 
     if (fab <= 0.f) {
-        fab = 10000.f;
+        fab = 100.f;
     }
 }
 
@@ -3860,22 +3860,7 @@ void ImProcFunctions::transit_shapedetect(int senstype, LabImage * bufexporig, L
                     }
 
                     if (previewcol  || previewexp || previewSH) {
-                        clc = 200.f;
-
-                        if (senstype == 1) {
-                            clc = 60.f;
-                        }
-
-                        if (senstype == 0) {
-                            cla = 0.f;
-                            clb = 200.f;
-                        }
-
-                        if (senstype == 1) {
-                            cla = 0.f;
-                            clb = 50.f;
-                        }
-
+                        clc = settings->previewselection * 100.f;//between 100 and 10000 to obtain "good" result 
                     }
 
                     float reducdE = 0.f;
@@ -3979,12 +3964,19 @@ void ImProcFunctions::transit_shapedetect(int senstype, LabImage * bufexporig, L
                                         flia = flib = ((100.f + realstrchdE) / 100.f);
                                     } else if (senstype == 1) {
                                         // printf("rdE=%f chdE=%f", realstradE, realstrchdE);
-                                        flia = (100.f + realstradE + 100.f * realstrchdE) / 100.f;
-                                        flib = (100.f + realstrbdE + 100.f * realstrchdE) / 100.f;
+                                       flia = (100.f + realstradE + 100.f * realstrchdE) / 100.f;
+                                       flib = (100.f + realstrbdE + 100.f * realstrchdE) / 100.f;
+                                        if (previewcol || previewexp || previewSH){
+                                            flia = (100.f + realstradE + realstrchdE) / 100.f;
+                                            flib = (100.f + realstrbdE + realstrchdE) / 100.f;
+                                        }
                                     } else if (senstype == 0) {
-                                        // printf("rdE=%f chdE=%f", realstradE, realstrchdE);
                                         flia = (100.f + 0.3f * lp.strengrid * realstradE + realstrchdE) / 100.f;
                                         flib = (100.f + 0.3f * lp.strengrid * realstrbdE + realstrchdE) / 100.f;
+                                        if (previewcol || previewexp || previewSH){
+                                            flia = (100.f + realstradE + realstrchdE) / 100.f;
+                                            flib = (100.f + realstrbdE + realstrchdE) / 100.f;
+                                        }
                                     }
 
                                     difa = chra * flia - original->a[y][x];
@@ -4076,9 +4068,17 @@ void ImProcFunctions::transit_shapedetect(int senstype, LabImage * bufexporig, L
                                     } else if (senstype == 1) {
                                         flia = (100.f + realstradE + 100.f * realstrchdE) / 100.f;
                                         flib = (100.f + realstrbdE + 100.f * realstrchdE) / 100.f;
+                                        if (previewcol || previewexp || previewSH){
+                                            flia = (100.f + realstradE + realstrchdE) / 100.f;
+                                            flib = (100.f + realstrbdE + realstrchdE) / 100.f;
+                                        }
                                     } else if (senstype == 0) {
                                         flia = (100.f + 0.3f * lp.strengrid * realstradE + realstrchdE) / 100.f;
                                         flib = (100.f + 0.3f * lp.strengrid * realstrbdE + realstrchdE) / 100.f;
+                                        if (previewcol || previewexp || previewSH){
+                                            flia = (100.f + realstradE + realstrchdE) / 100.f;
+                                            flib = (100.f + realstrbdE + realstrchdE) / 100.f;
+                                        }
                                     }
 
                                     difa = chra * flia - original->a[y][x];
diff --git a/rtengine/settings.h b/rtengine/settings.h
index a231f111a..99c378acb 100644
--- a/rtengine/settings.h
+++ b/rtengine/settings.h
@@ -84,6 +84,7 @@ public:
     double          reduchigh;
     double          reduclow;
     bool            detectshape;
+    int             previewselection;
 
 
     Glib::ustring   lensfunDbDirectory; ///< The directory containing the lensfun database. If empty, the system defaults will be used (as described in http://lensfun.sourceforge.net/manual/dbsearch.html)
diff --git a/rtgui/options.cc b/rtgui/options.cc
index 2719165e2..1f1bcb5d0 100644
--- a/rtgui/options.cc
+++ b/rtgui/options.cc
@@ -592,6 +592,7 @@ void Options::setDefaults()
     rtSettings.reduchigh = 0.85;//transition for luminance in scope
     rtSettings.reduclow = 0.85;//transition for luminance out scope
     rtSettings.detectshape = true;//experimental new detection shape
+    rtSettings.previewselection = 5;//betwen 1 to 40
 
 // end locallab
 
@@ -1614,6 +1615,10 @@ void Options::readFromFile(Glib::ustring fname)
 
                 //if( keyFile.has_key ("Color Management", "Ciebadpixgauss")) rtSettings.ciebadpixgauss = keyFile.get_boolean("Color Management", "Ciebadpixgauss");
 
+                if (keyFile.has_key("Color Management", "Previewselection")) {//Intensity of preview selection deltaE
+                    rtSettings.previewselection = keyFile.get_integer("Color Management", "Previewselection");
+                }
+
             }
 
             if (keyFile.has_group("ICC Profile Creator")) {
@@ -2196,6 +2201,7 @@ void Options::saveToFile(Glib::ustring fname)
         //keyFile.set_double  ("Color Management", "Colortoningab", rtSettings.colortoningab);
         //keyFile.set_double  ("Color Management", "Decaction", rtSettings.decaction);
         keyFile.set_string("Color Management", "ClutsDirectory", clutsDir);
+        keyFile.set_integer("Color Management", "Previewselection", rtSettings.previewselection);
 
         keyFile.set_string("ICC Profile Creator", "PimariesPreset", ICCPC_primariesPreset);
         keyFile.set_double("ICC Profile Creator", "RedPrimaryX", ICCPC_redPrimaryX);