diff --git a/rtdata/languages/default b/rtdata/languages/default
index aeb5664e8..ca1d0ac76 100644
--- a/rtdata/languages/default
+++ b/rtdata/languages/default
@@ -658,6 +658,7 @@ HISTORY_MSG_425;Retinex - Log base
 HISTORY_MSG_426;Retinex - Hue equalizer
 HISTORY_MSG_427;Retinex - Iterations
 HISTORY_MSG_428;Retinex - T. Gradient
+HISTORY_MSG_429;Retinex - S. Gradient
 HISTORY_NEWSNAPSHOT;Add
 HISTORY_NEWSNAPSHOT_TOOLTIP;Shortcut: <b>Alt-s</b>
 HISTORY_SNAPSHOTS;Snapshots
@@ -1660,6 +1661,8 @@ TP_RETINEX_ITER;Iterations (Tone-mapping)
 TP_RETINEX_ITER_TOOLTIP;Simulate a tone-mapping operator\nHigh values increase the processing time
 TP_RETINEX_GRAD;Transmission gradient
 TP_RETINEX_GRAD_TOOLTIP;If slider at 0, all iterations are identical\nIf > 0 Variance and Threshold are reduce when iteration increases and conversely
+TP_RETINEX_GRADS;Strength gradient
+TP_RETINEX_GRAD_TOOLTIP;If slider at 0, all iterations are identical\nIf > 0 Strength is reduce when iteration increases and conversely
 TP_RETINEX_LABEL;Retinex
 TP_RETINEX_LABSPACE;L*a*b*
 TP_RETINEX_LOW;Low
diff --git a/rtengine/ipretinex.cc b/rtengine/ipretinex.cc
index 1f6602b62..b07af2e14 100644
--- a/rtengine/ipretinex.cc
+++ b/rtengine/ipretinex.cc
@@ -223,6 +223,7 @@ void RawImageSource::MSR(float** luminance, float** originalLuminance, float **e
         int nei = (int) 2.8f * deh.neigh; //def = 220
         float vart = (float)deh.vart / 100.f;//variance
         float gradvart = (float)deh.grad;
+        float gradstr = (float)deh.grads;
         float strength = (float) deh.str / 100.f; // Blend with original L channel data
         float limD = (float) deh.limd;
         limD = pow(limD, 1.7f);//about 2500 enough
@@ -274,6 +275,7 @@ void RawImageSource::MSR(float** luminance, float** originalLuminance, float **e
             moderetinex = 3;
         }
         for(int it=1; it<iter+1; it++) {//iter nb max of iterations
+            float grads;
             float grad=1.f;
             float sc = 3.f;
             if(gradient==0) {
@@ -334,6 +336,29 @@ void RawImageSource::MSR(float** luminance, float** originalLuminance, float **e
                 ilimdx=ilimD;
             }
             scal=round(sc);
+            float strengthx;
+            float ks=1.f;
+
+            if(gradstr!=0) {
+                if(gradstr==1) {
+                    if(it <= 3) ks=-0.3f*it+1.6f;
+                    else ks = 0.5f;
+                }
+                else if(gradstr==2) {
+                    if(it <= 3) ks=-0.6f*it+2.2f;
+                    else ks = 0.3f;
+                }
+                else if(gradstr==-1) {
+                    if(it <= 3) ks=0.2f*it+0.6f;
+                    else ks = 1.2f;
+                }
+                else if(gradstr==-2) {
+                    if(it <= 3) ks=0.4f*it+0.2f;
+                    else ks = 1.5f;
+                }
+            }
+            strengthx=ks*strength;
+
             float aahi = 49.f / 99.f; ////reduce sensibility 50%
             float bbhi = 1.f - aahi;
             float high;
@@ -569,9 +594,9 @@ void RawImageSource::MSR(float** luminance, float** originalLuminance, float **e
                             cdmin = cd;
                         }
 
-                        float str = strength;
+                        float str = strengthx;
 
-                        if(lhutili) {  // S=f(H)
+                        if(lhutili  && it==1) {  // S=f(H)
                             {
                                 float HH = exLuminance[i][j];
                                 float valparam;
@@ -605,7 +630,7 @@ void RawImageSource::MSR(float** luminance, float** originalLuminance, float **e
             Tmin = mintr;
             Tmax = maxtr;
 
-            if (shcurve) {
+            if (shcurve && it==1) {
                 delete shcurve;
             }
         }
diff --git a/rtengine/procevents.h b/rtengine/procevents.h
index ae348316f..6f1d7144a 100644
--- a/rtengine/procevents.h
+++ b/rtengine/procevents.h
@@ -456,6 +456,7 @@ enum ProcEvent {
     EvRetinexlhcurve = 425,
     EvLiter = 426,
     EvLgrad = 427,
+    EvLgrads = 428,
     NUMOFEVENTS
 };
 }
diff --git a/rtengine/procparams.cc b/rtengine/procparams.cc
index ed57f50d3..6c737f8a2 100644
--- a/rtengine/procparams.cc
+++ b/rtengine/procparams.cc
@@ -144,6 +144,7 @@ void RetinexParams::setDefaults()
     scal        = 3;
     iter = 1;
     grad = 1;
+    grads = 1;
     gam        = 1.30;
     slope   = 3.;
     neigh      = 80;
@@ -1451,7 +1452,11 @@ int ProcParams::save (Glib::ustring fname, Glib::ustring fname2, bool fnameAbsol
     }
 
     if (!pedited || pedited->retinex.grad) {
-        keyFile.set_integer ("Retinex", "Grad",               retinex.iter);
+        keyFile.set_integer ("Retinex", "Grad",               retinex.grad);
+    }
+
+    if (!pedited || pedited->retinex.grads) {
+        keyFile.set_integer ("Retinex", "Grads",               retinex.grads);
     }
 
     if (!pedited || pedited->retinex.gam) {
@@ -3877,6 +3882,14 @@ int ProcParams::load (Glib::ustring fname, ParamsEdited* pedited)
                 }
             }
 
+            if (keyFile.has_key ("Retinex", "Grads"))     {
+                retinex.grads   = keyFile.get_integer ("Retinex", "Grads");
+
+                if (pedited) {
+                    pedited->retinex.grads = true;
+                }
+            }
+
             if (keyFile.has_key ("Retinex", "Gam"))     {
                 retinex.gam   = keyFile.get_double ("Retinex", "Gam");
 
@@ -7350,6 +7363,7 @@ bool ProcParams::operator== (const ProcParams& other)
         && retinex.scal == other.retinex.scal
         && retinex.iter == other.retinex.iter
         && retinex.grad == other.retinex.grad
+        && retinex.grads == other.retinex.grads
         && retinex.gam == other.retinex.gam
         && retinex.slope == other.retinex.slope
         && retinex.neigh == other.retinex.neigh
diff --git a/rtengine/procparams.h b/rtengine/procparams.h
index 1226d1584..2b8b7ada6 100644
--- a/rtengine/procparams.h
+++ b/rtengine/procparams.h
@@ -277,6 +277,7 @@ public:
     int     scal;
     int     iter;
     int     grad;
+    int     grads;
     double  gam;
     double  slope;
     int     neigh;
diff --git a/rtengine/refreshmap.cc b/rtengine/refreshmap.cc
index 88338f06c..30373a35e 100644
--- a/rtengine/refreshmap.cc
+++ b/rtengine/refreshmap.cc
@@ -455,7 +455,8 @@ int refreshmap[rtengine::NUMOFEVENTS] = {
 //    DEMOSAIC,          // EvLgrbl
     DEMOSAIC,          // EvRetinexlhcurve
     RETINEX,           // EvLiter
-    RETINEX           // EvLgrad
+    RETINEX,           // EvLgrad
+    RETINEX           // EvLgrads
 
 };
 
diff --git a/rtgui/paramsedited.cc b/rtgui/paramsedited.cc
index 600a68af4..2efed572e 100644
--- a/rtgui/paramsedited.cc
+++ b/rtgui/paramsedited.cc
@@ -60,6 +60,7 @@ void ParamsEdited::set (bool v)
     retinex.scal    = v;
     retinex.iter    = v;
     retinex.grad    = v;
+    retinex.grads    = v;
     retinex.gam    = v;
     retinex.slope    = v;
     retinex.neigh    = v;
@@ -539,6 +540,7 @@ void ParamsEdited::initFrom (const std::vector<rtengine::procparams::ProcParams>
         retinex.scal = retinex.scal && p.retinex.scal == other.retinex.scal;
         retinex.iter = retinex.iter && p.retinex.iter == other.retinex.iter;
         retinex.grad = retinex.grad && p.retinex.grad == other.retinex.grad;
+        retinex.grads = retinex.grads && p.retinex.grads == other.retinex.grads;
         retinex.gam = retinex.gam && p.retinex.gam == other.retinex.gam;
         retinex.slope = retinex.slope && p.retinex.slope == other.retinex.slope;
         retinex.neigh = retinex.neigh && p.retinex.neigh == other.retinex.neigh;
@@ -1098,6 +1100,10 @@ void ParamsEdited::combine (rtengine::procparams::ProcParams& toEdit, const rten
         toEdit.retinex.grad    = mods.retinex.grad;
     }
 
+    if (retinex.grads) {
+        toEdit.retinex.grads    = mods.retinex.grads;
+    }
+
 //    if (retinex.scal) {
 //        toEdit.retinex.scal   = dontforceSet && options.baBehav[ADDSET_RETI_SCAL] ? toEdit.retinex.scal + mods.retinex.scal : mods.retinex.scal;
 //    }
diff --git a/rtgui/paramsedited.h b/rtgui/paramsedited.h
index ed1f07aec..f174c8d52 100644
--- a/rtgui/paramsedited.h
+++ b/rtgui/paramsedited.h
@@ -63,6 +63,7 @@ public:
     bool scal;
     bool iter;
     bool grad;
+    bool grads;
     bool gam;
     bool slope;
     bool neigh;
diff --git a/rtgui/retinex.cc b/rtgui/retinex.cc
index 0578c3e57..0bd5c28ae 100644
--- a/rtgui/retinex.cc
+++ b/rtgui/retinex.cc
@@ -147,6 +147,7 @@ Retinex::Retinex () : FoldableToolPanel(this, "retinex", M("TP_RETINEX_LABEL"),
     scal   = Gtk::manage (new Adjuster (M("TP_RETINEX_SCALES"), -1, 5., 1., 3.));
     iter   = Gtk::manage (new Adjuster (M("TP_RETINEX_ITER"), 1, 5., 1., 1.));
     grad   = Gtk::manage (new Adjuster (M("TP_RETINEX_GRAD"), -2., 2., 1., 1.));
+    grads   = Gtk::manage (new Adjuster (M("TP_RETINEX_GRADS"), -2., 2., 1., 1.));
     gain   = Gtk::manage (new Adjuster (M("TP_RETINEX_GAIN"), 20, 200, 1, 50));
     offs   = Gtk::manage (new Adjuster (M("TP_RETINEX_OFFSET"), -10000, 10000, 1, 0));
 //    vart   = Gtk::manage (new Adjuster (M("TP_RETINEX_VARIANCE"), 50, 500, 1, 125));
@@ -157,6 +158,7 @@ Retinex::Retinex () : FoldableToolPanel(this, "retinex", M("TP_RETINEX_LABEL"),
     scal->set_tooltip_markup (M("TP_RETINEX_SCALES_TOOLTIP"));
     iter->set_tooltip_markup (M("TP_RETINEX_ITER_TOOLTIP"));
     grad->set_tooltip_markup (M("TP_RETINEX_GRAD_TOOLTIP"));
+    grads->set_tooltip_markup (M("TP_RETINEX_GRADS_TOOLTIP"));
 //    vart->set_tooltip_markup (M("TP_RETINEX_VARIANCE_TOOLTIP"));
     limd->set_tooltip_markup (M("TP_RETINEX_THRESHOLD_TOOLTIP"));
     baselog->set_tooltip_markup (M("TP_RETINEX_BASELOG_TOOLTIP"));
@@ -224,6 +226,9 @@ Retinex::Retinex () : FoldableToolPanel(this, "retinex", M("TP_RETINEX_LABEL"),
     settingsVBox->pack_start (*grad);
     grad->show ();
 
+    settingsVBox->pack_start (*grads);
+    grads->show ();
+
     settingsVBox->pack_start (*gain);
     gain->show ();
 
@@ -289,6 +294,12 @@ Retinex::Retinex () : FoldableToolPanel(this, "retinex", M("TP_RETINEX_LABEL"),
         grad->delay = 200;
     }
 
+    grads->setAdjusterListener (this);
+
+    if (grads->delay < 200) {
+        grads->delay = 200;
+    }
+
     gam->setAdjusterListener (this);
 
     if (gam->delay < 500) {
@@ -378,6 +389,7 @@ void Retinex::neutral_pressed ()
     scal->resetValue(false);
     iter->resetValue(false);
     grad->resetValue(false);
+    grads->resetValue(false);
     vart->resetValue(false);
     limd->resetValue(false);
     highl->resetValue(false);
@@ -503,6 +515,7 @@ void Retinex::read (const ProcParams* pp, const ParamsEdited* pedited)
         scal->setEditedState (pedited->retinex.scal ? Edited : UnEdited);
         iter->setEditedState (pedited->retinex.iter ? Edited : UnEdited);
         grad->setEditedState (pedited->retinex.grad ? Edited : UnEdited);
+        grads->setEditedState (pedited->retinex.grads ? Edited : UnEdited);
         neigh->setEditedState (pedited->retinex.neigh ? Edited : UnEdited);
         gam->setEditedState (pedited->retinex.gam ? Edited : UnEdited);
         slope->setEditedState (pedited->retinex.slope ? Edited : UnEdited);
@@ -543,6 +556,7 @@ void Retinex::read (const ProcParams* pp, const ParamsEdited* pedited)
     scal->setValue      (pp->retinex.scal);
     iter->setValue      (pp->retinex.iter);
     grad->setValue      (pp->retinex.grad);
+    grads->setValue      (pp->retinex.grads);
     vart->setValue  (pp->retinex.vart);
     limd->setValue  (pp->retinex.limd);
     gam->setValue      (pp->retinex.gam);
@@ -553,10 +567,12 @@ void Retinex::read (const ProcParams* pp, const ParamsEdited* pedited)
     if(pp->retinex.iter == 1)   {
         grad->set_sensitive(false);
         scal->set_sensitive(false);
+        grads->set_sensitive(false);
     }
     else {
         grad->set_sensitive(true);
         scal->set_sensitive(true);
+        grads->set_sensitive(true);
     }
 
     setEnabled (pp->retinex.enabled);
@@ -627,6 +643,7 @@ void Retinex::write (ProcParams* pp, ParamsEdited* pedited)
     pp->retinex.scal      = (int)scal->getValue ();
     pp->retinex.iter      = (int) iter->getValue ();
     pp->retinex.grad      = (int) grad->getValue ();
+    pp->retinex.grads      = (int) grads->getValue ();
     pp->retinex.gam      = gam->getValue ();
     pp->retinex.slope      = slope->getValue ();
     pp->retinex.neigh    = neigh->getValue ();
@@ -654,6 +671,7 @@ void Retinex::write (ProcParams* pp, ParamsEdited* pedited)
         pedited->retinex.scal     = scal->getEditedState ();
         pedited->retinex.iter     = iter->getEditedState ();
         pedited->retinex.grad     = grad->getEditedState ();
+        pedited->retinex.grads     = grads->getEditedState ();
         pedited->retinex.gam     = gam->getEditedState ();
         pedited->retinex.slope     = slope->getEditedState ();
         pedited->retinex.neigh   = neigh->getEditedState ();
@@ -811,6 +829,7 @@ void Retinex::setDefaults (const ProcParams* defParams, const ParamsEdited* pedi
     scal->setDefault (defParams->retinex.scal);
     iter->setDefault (defParams->retinex.iter);
     grad->setDefault (defParams->retinex.grad);
+    grads->setDefault (defParams->retinex.grads);
     vart->setDefault (defParams->retinex.vart);
     limd->setDefault (defParams->retinex.limd);
     highl->setDefault (defParams->retinex.highl);
@@ -827,6 +846,7 @@ void Retinex::setDefaults (const ProcParams* defParams, const ParamsEdited* pedi
         scal->setDefaultEditedState (pedited->retinex.scal ? Edited : UnEdited);
         iter->setDefaultEditedState (pedited->retinex.iter ? Edited : UnEdited);
         grad->setDefaultEditedState (pedited->retinex.grad ? Edited : UnEdited);
+        grads->setDefaultEditedState (pedited->retinex.grads ? Edited : UnEdited);
         vart->setDefaultEditedState (pedited->retinex.vart ? Edited : UnEdited);
         limd->setDefaultEditedState (pedited->retinex.limd ? Edited : UnEdited);
         highl->setDefaultEditedState (pedited->retinex.highl ? Edited : UnEdited);
@@ -848,6 +868,7 @@ void Retinex::setDefaults (const ProcParams* defParams, const ParamsEdited* pedi
         scal->setDefaultEditedState (Irrelevant);
         iter->setDefaultEditedState (Irrelevant);
         grad->setDefaultEditedState (Irrelevant);
+        grads->setDefaultEditedState (Irrelevant);
         gam->setDefaultEditedState (Irrelevant);
         slope->setDefaultEditedState (Irrelevant);
     }
@@ -875,10 +896,12 @@ void Retinex::adjusterChanged (Adjuster* a, double newval)
     if(iter->getTextValue() > "1") {
         scal->set_sensitive(true);
         grad->set_sensitive(true);
+        grads->set_sensitive(true);
     }
     else {
         scal->set_sensitive(false);
         grad->set_sensitive(false);
+        grads->set_sensitive(false);
     }
 
 
@@ -892,6 +915,8 @@ void Retinex::adjusterChanged (Adjuster* a, double newval)
         listener->panelChanged (EvLiter, iter->getTextValue());
     } else if (a == grad) {
         listener->panelChanged (EvLgrad, grad->getTextValue());
+    } else if (a == grads) {
+        listener->panelChanged (EvLgrads, grads->getTextValue());
     } else if (a == gain) {
         listener->panelChanged (EvLgain, gain->getTextValue());
     } else if (a == offs) {
@@ -962,6 +987,7 @@ void Retinex::trimValues (rtengine::procparams::ProcParams* pp)
     scal->trimValue(pp->retinex.scal);
     iter->trimValue(pp->retinex.iter);
     grad->trimValue(pp->retinex.grad);
+    grads->trimValue(pp->retinex.grads);
     neigh->trimValue(pp->retinex.neigh);
     gain->trimValue(pp->retinex.gain);
     offs->trimValue(pp->retinex.offs);
@@ -1037,6 +1063,7 @@ void Retinex::setBatchMode (bool batchMode)
     scal->showEditedCB ();
     iter->showEditedCB ();
     grad->showEditedCB ();
+    grads->showEditedCB ();
     gam->showEditedCB ();
     slope->showEditedCB ();
     vart->showEditedCB ();
diff --git a/rtgui/retinex.h b/rtgui/retinex.h
index 499b0ef0f..e014bed5d 100644
--- a/rtgui/retinex.h
+++ b/rtgui/retinex.h
@@ -25,6 +25,7 @@ protected:
     Adjuster* str;
     Adjuster* scal;
     Adjuster* grad;
+    Adjuster* grads;
     Adjuster* iter;
     Adjuster* neigh;
     Adjuster* gain;