diff --git a/rtdata/languages/default b/rtdata/languages/default
index bebed7ff5..ed8756b21 100644
--- a/rtdata/languages/default
+++ b/rtdata/languages/default
@@ -1042,6 +1042,7 @@ HISTORY_MSG_801;Local - Color ToneCurve Special
 HISTORY_MSG_802;Local - Contrast threshold
 HISTORY_MSG_803;Local - Color Merge
 HISTORY_MSG_804;Local - Color mask Structure
+HISTORY_MSG_805;Local - Blur Noise mask Structure
 HISTORY_MSG_CLAMPOOG;Clip out-of-gamut colors
 HISTORY_MSG_COLORTONING_LABGRID_VALUE;CT - Color correction
 HISTORY_MSG_COLORTONING_LABREGION_AB;CT - Color correction
diff --git a/rtengine/iplocallab.cc b/rtengine/iplocallab.cc
index d68ca69b2..95e7f5e00 100644
--- a/rtengine/iplocallab.cc
+++ b/rtengine/iplocallab.cc
@@ -7649,6 +7649,20 @@ void ImProcFunctions::Lab_Local(int call, int sp, float** shbuffer, LabImage * o
             }
 
             if (lp.showmaskblmet == 2  || lp.enablMask || lp.showmaskblmet == 3 || lp.showmaskblmet == 4) {
+                JaggedArray<float> blendstru(GW, GH);
+                float strumask = 0.01f * (float) params->locallab.spots.at(sp).strumaskbl;
+
+                if(strumask > 0.f){
+                    buildBlendMask(bufgb->L, blendstru, GW, GH, strumask, 1.f);
+                    float radblur = 0.02f * lp.radmabl;
+                    float rm = radblur / sk;
+
+                    if (rm > 0) {
+                        float **mb = blendstru;
+                        gaussianBlur(mb, mb, GW, GH, rm);
+                    }
+            }
+
 #ifdef _OPENMP
                 #pragma omp parallel for schedule(dynamic,16)
 #endif
@@ -7657,6 +7671,11 @@ void ImProcFunctions::Lab_Local(int call, int sp, float** shbuffer, LabImage * o
                     for (int jr = 0; jr < GW; jr++) {
                         float kmaskLexp = 0;
                         float kmaskCH = 0;
+                        float kmasstru = 0.f;
+
+                        if(strumask > 0.f){
+                            kmasstru = bufgb->L[ir][jr]* blendstru[ir][jr];
+                        }
 
                         if (locllmasblCurve  && llmasblutili) {
                             float ligh = bufgb->L[ir][jr] / 32768.f;
@@ -7688,7 +7707,7 @@ void ImProcFunctions::Lab_Local(int call, int sp, float** shbuffer, LabImage * o
                             kmaskLexp += 32768.f * valHH;
                         }
 
-                        bufmaskblurbl->L[ir][jr] = CLIPLOC(kmaskLexp);
+                        bufmaskblurbl->L[ir][jr] = CLIPLOC(kmaskLexp +  kmasstru);
                         bufmaskblurbl->a[ir][jr] = kmaskCH;
                         bufmaskblurbl->b[ir][jr] = kmaskCH;
                         ble[ir][jr] = bufmaskblurbl->L[ir][jr] / 32768.f;
@@ -12572,6 +12591,7 @@ void ImProcFunctions::Lab_Local(int call, int sp, float** shbuffer, LabImage * o
             int sco = params->locallab.spots.at(sp).scopemask;
             int shortcu = lp.mergemet; //params->locallab.spots.at(sp).shortc;
             int lumask = params->locallab.spots.at(sp).lumask;
+            float strumask = 0.01f *(float) params->locallab.spots.at(sp).strumaskcol;
 
             const int limscope = 80;
             const float mindE = 2.f + MINSCOPE * sco * lp.thr;
@@ -12582,7 +12602,7 @@ void ImProcFunctions::Lab_Local(int call, int sp, float** shbuffer, LabImage * o
             float anchorcd = 50.f;
 
             maskcalccol(false, pde, GW, GH, 0, 0, sk, cx, cy, bufcolorig.get(), bufmaskblurcol.get(), originalmaskcol.get(), original, inv, lp,
-                        0.f,
+                        strumask,
                         locccmasCurve, lcmasutili, locllmasCurve, llmasutili, lochhmasCurve, lhmasutili, multiThread,
                         enaMask, showmaske, deltaE, modmask, zero, modif, chrom, rad, lap, gamma, slope, blendm, shado, amountcd, anchorcd, lmasklocalcurve, localmaskutili, loclmasCurvecolwav, lmasutilicolwav,
                         level_bl, level_hl, level_br, level_hr,
diff --git a/rtengine/procevents.h b/rtengine/procevents.h
index 1b33e1dcb..a18087bab 100644
--- a/rtengine/procevents.h
+++ b/rtengine/procevents.h
@@ -828,6 +828,7 @@ enum ProcEventCode {
     Evlocallabconthrcol = 801,
     EvLocallabmerMethod = 802,
     Evlocallabstrumaskcol = 803,
+    Evlocallabstrumaskbl = 804,
     NUMOFEVENTS
 };
 
diff --git a/rtengine/procparams.cc b/rtengine/procparams.cc
index 85cfdb287..351827128 100644
--- a/rtengine/procparams.cc
+++ b/rtengine/procparams.cc
@@ -2598,6 +2598,7 @@ LocallabParams::LocallabSpot::LocallabSpot() :
     slomaskbl(0.0),
     lapmaskbl(0.0),
     shadmaskbl(0),
+    strumaskbl(0),
     Lmaskblcurve{(double)DCT_NURBS, 0.0, 0.0, 1.0, 1.0},
     LLmaskblcurvewav{(double)FCT_MinMaxCPoints, 0.0, 0.5, 0.35, 0.35, 1., 0.5, 0.35, 0.35},
     csthresholdblur(0, 0, 6, 5, false),
@@ -2925,6 +2926,7 @@ bool LocallabParams::LocallabSpot::operator ==(const LocallabSpot& other) const
         && slomaskbl == other.slomaskbl
         && lapmaskbl == other.lapmaskbl
         && shadmaskbl == other.shadmaskbl
+        && strumaskbl == other.strumaskbl
         && Lmaskblcurve == other.Lmaskblcurve
         && LLmaskblcurvewav == other.LLmaskblcurvewav
         && csthresholdblur == other.csthresholdblur
@@ -4231,6 +4233,7 @@ int ProcParams::save(const Glib::ustring& fname, const Glib::ustring& fname2, bo
                 saveToKeyfile(!pedited || pedited->locallab.spots.at(i).slomaskbl, "Locallab", "Slomaskbl_" + std::to_string(i), spot.slomaskbl, keyFile);
                 saveToKeyfile(!pedited || pedited->locallab.spots.at(i).lapmaskbl, "Locallab", "Lapmaskbl_" + std::to_string(i), spot.lapmaskbl, keyFile);
                 saveToKeyfile(!pedited || pedited->locallab.spots.at(i).shadmaskbl, "Locallab", "shadmaskbl_" + std::to_string(i), spot.shadmaskbl, keyFile);
+                saveToKeyfile(!pedited || pedited->locallab.spots.at(i).strumaskbl, "Locallab", "strumaskbl_" + std::to_string(i), spot.strumaskbl, keyFile);
                 saveToKeyfile(!pedited || pedited->locallab.spots.at(i).Lmaskblcurve, "Locallab", "LmaskblCurve_" + std::to_string(i), spot.Lmaskblcurve, keyFile);
                 saveToKeyfile(!pedited || pedited->locallab.spots.at(i).LLmaskblcurvewav, "Locallab", "LLmaskblCurvewav_" + std::to_string(i), spot.LLmaskblcurvewav, keyFile);
                 saveToKeyfile(!pedited || pedited->locallab.spots.at(i).csthresholdblur, "Locallab", "CSThresholdblur_" + std::to_string(i), spot.csthresholdblur.toVector(), keyFile);
@@ -5675,6 +5678,7 @@ int ProcParams::load(const Glib::ustring& fname, ParamsEdited* pedited)
                 assignFromKeyfile(keyFile, "Locallab", "Slomaskbl_" + std::to_string(i), pedited, spot.slomaskbl, spotEdited.slomaskbl);
                 assignFromKeyfile(keyFile, "Locallab", "Lapmaskbl_" + std::to_string(i), pedited, spot.lapmaskbl, spotEdited.lapmaskbl);
                 assignFromKeyfile(keyFile, "Locallab", "shadmaskbl_" + std::to_string(i), pedited, spot.shadmaskbl, spotEdited.shadmaskbl);
+                assignFromKeyfile(keyFile, "Locallab", "strumaskbl_" + std::to_string(i), pedited, spot.strumaskbl, spotEdited.strumaskbl);
                 assignFromKeyfile(keyFile, "Locallab", "LmaskblCurve_" + std::to_string(i), pedited, spot.Lmaskblcurve, spotEdited.Lmaskblcurve);
                 assignFromKeyfile(keyFile, "Locallab", "LLmaskblCurvewav_" + std::to_string(i), pedited, spot.LLmaskblcurvewav, spotEdited.LLmaskblcurvewav);
                 if (keyFile.has_key("Locallab", "CSThresholdblur_" + std::to_string(i))) {
diff --git a/rtengine/procparams.h b/rtengine/procparams.h
index b6a092fec..3827c4b0a 100644
--- a/rtengine/procparams.h
+++ b/rtengine/procparams.h
@@ -1142,6 +1142,7 @@ struct LocallabParams {
         double slomaskbl;
         double lapmaskbl;
         int shadmaskbl;
+        int strumaskbl;
         std::vector<double> Lmaskblcurve;
         std::vector<double> LLmaskblcurvewav;
         Threshold<int> csthresholdblur;
diff --git a/rtengine/refreshmap.cc b/rtengine/refreshmap.cc
index 77554aa49..0b7245c8a 100644
--- a/rtengine/refreshmap.cc
+++ b/rtengine/refreshmap.cc
@@ -831,7 +831,8 @@ int refreshmap[rtengine::NUMOFEVENTS] = {
     LUMINANCECURVE,         // EvLocallabspecial
     LUMINANCECURVE,          //EvLocallabconthrcol
     LUMINANCECURVE,          //EvLocallabmerMethod
-    LUMINANCECURVE          //EvLocallabstrumaskcol
+    LUMINANCECURVE,          //EvLocallabstrumaskcol
+    LUMINANCECURVE          //EvLocallabstrumaskbl
 };
 
 namespace rtengine
diff --git a/rtgui/locallab.cc b/rtgui/locallab.cc
index a46c44829..73316654c 100644
--- a/rtgui/locallab.cc
+++ b/rtgui/locallab.cc
@@ -359,6 +359,7 @@ shadmaskbl(Gtk::manage(new Adjuster(M("TP_LOCALLAB_HIGHMASKCOL"), 0, 100, 1, 0))
 isogr(Gtk::manage(new Adjuster(M("TP_LOCALLAB_ISOGR"), 20, 6400, 1, 400))),
 strengr(Gtk::manage(new Adjuster(M("TP_LOCALLAB_STRENGR"), 0, 100, 1, 0))),
 scalegr(Gtk::manage(new Adjuster(M("TP_LOCALLAB_SCALEGR"), 0, 100, 1, 100))),
+strumaskbl(Gtk::manage(new Adjuster(M("TP_LOCALLAB_STRUMASKCOL"), 0, 100, 1, 0))),
 // Tone Mapping
 stren(Gtk::manage(new Adjuster(M("TP_LOCALLAB_STREN"), -0.5, 2.0, 0.01, 0.5))),
 gamma(Gtk::manage(new Adjuster(M("TP_LOCALLAB_GAM"), 0.4, 4.0, 0.11, 1.0))),
@@ -2431,11 +2432,15 @@ pe(nullptr)
     slomaskbl->setAdjusterListener(this);
     lapmaskbl->setAdjusterListener(this);
     shadmaskbl->setAdjusterListener(this);
+    strumaskbl->setAdjusterListener(this);
+    Gtk::HSeparator* const separatorstrubl = Gtk::manage(new  Gtk::HSeparator());
 
     ToolParamBlock* const maskblBox = Gtk::manage(new ToolParamBlock());
     maskblBox->pack_start(*showmaskblMethod, Gtk::PACK_SHRINK, 4);
     maskblBox->pack_start(*enablMask, Gtk::PACK_SHRINK, 0);
     maskblBox->pack_start(*maskblCurveEditorG, Gtk::PACK_SHRINK, 4); // Padding is mandatory to correct behavior of curve editor
+    maskblBox->pack_start(*strumaskbl, Gtk::PACK_SHRINK, 0);
+    maskblBox->pack_start(*separatorstrubl, Gtk::PACK_SHRINK, 2);
     maskblBox->pack_start(*blendmaskbl, Gtk::PACK_SHRINK, 0);
     maskblBox->pack_start(*radmaskbl, Gtk::PACK_SHRINK, 0);
     maskblBox->pack_start(*lapmaskbl, Gtk::PACK_SHRINK, 0);
@@ -3876,6 +3881,7 @@ void Locallab::write(rtengine::procparams::ProcParams* pp, ParamsEdited* pedited
                     pp->locallab.spots.at(pp->locallab.selspot).slomaskbl = slomaskbl->getValue();
                     pp->locallab.spots.at(pp->locallab.selspot).lapmaskbl = lapmaskbl->getValue();
                     pp->locallab.spots.at(pp->locallab.selspot).shadmaskbl = shadmaskbl->getIntValue();
+                    pp->locallab.spots.at(pp->locallab.selspot).strumaskbl = strumaskbl->getIntValue();
                     pp->locallab.spots.at(pp->locallab.selspot).fftwbl = fftwbl->get_active();
                     pp->locallab.spots.at(pp->locallab.selspot).Lmaskblcurve = Lmaskblshape->getCurve();
                     pp->locallab.spots.at(pp->locallab.selspot).LLmaskblcurvewav = LLmaskblshapewav->getCurve();
@@ -4216,6 +4222,7 @@ void Locallab::write(rtengine::procparams::ProcParams* pp, ParamsEdited* pedited
                         pe->locallab.spots.at(pp->locallab.selspot).slomaskbl = pe->locallab.spots.at(pp->locallab.selspot).slomaskbl || slomaskbl->getEditedState();
                         pe->locallab.spots.at(pp->locallab.selspot).lapmaskbl = pe->locallab.spots.at(pp->locallab.selspot).lapmaskbl || lapmaskbl->getEditedState();
                         pe->locallab.spots.at(pp->locallab.selspot).shadmaskbl = pe->locallab.spots.at(pp->locallab.selspot).shadmaskbl || shadmaskbl->getEditedState();
+                        pe->locallab.spots.at(pp->locallab.selspot).strumaskbl = pe->locallab.spots.at(pp->locallab.selspot).strumaskbl || strumaskbl->getEditedState();
                         pe->locallab.spots.at(pp->locallab.selspot).fftwbl = pe->locallab.spots.at(pp->locallab.selspot).fftwbl || !fftwbl->get_inconsistent();
                         pe->locallab.spots.at(pp->locallab.selspot).Lmaskblcurve = pe->locallab.spots.at(pp->locallab.selspot).Lmaskblcurve || !Lmaskblshape->isUnChanged();
                         pe->locallab.spots.at(pp->locallab.selspot).LLmaskblcurvewav = pe->locallab.spots.at(pp->locallab.selspot).LLmaskblcurvewav || !LLmaskblshapewav->isUnChanged();
@@ -4543,6 +4550,7 @@ void Locallab::write(rtengine::procparams::ProcParams* pp, ParamsEdited* pedited
                         pedited->locallab.spots.at(pp->locallab.selspot).slomaskbl = pedited->locallab.spots.at(pp->locallab.selspot).slomaskbl || slomaskbl->getEditedState();
                         pedited->locallab.spots.at(pp->locallab.selspot).lapmaskbl = pedited->locallab.spots.at(pp->locallab.selspot).lapmaskbl || lapmaskbl->getEditedState();
                         pedited->locallab.spots.at(pp->locallab.selspot).shadmaskbl = pedited->locallab.spots.at(pp->locallab.selspot).shadmaskbl || shadmaskbl->getEditedState();
+                        pedited->locallab.spots.at(pp->locallab.selspot).strumaskbl = pedited->locallab.spots.at(pp->locallab.selspot).strumaskbl || strumaskbl->getEditedState();
                         pedited->locallab.spots.at(pp->locallab.selspot).fftwbl = pedited->locallab.spots.at(pp->locallab.selspot).fftwbl || !fftwbl->get_inconsistent();
                         pedited->locallab.spots.at(pp->locallab.selspot).Lmaskblcurve = pedited->locallab.spots.at(pp->locallab.selspot).Lmaskblcurve || !Lmaskblshape->isUnChanged();
                         pedited->locallab.spots.at(pp->locallab.selspot).LLmaskblcurvewav = pedited->locallab.spots.at(pp->locallab.selspot).LLmaskblcurvewav || !LLmaskblshapewav->isUnChanged();
@@ -6620,6 +6628,7 @@ void Locallab::setDefaults(const rtengine::procparams::ProcParams * defParams, c
     slomaskbl->setDefault(defSpot->slomaskbl);
     lapmaskbl->setDefault(defSpot->lapmaskbl);
     shadmaskbl->setDefault(defSpot->shadmaskbl);
+    strumaskbl->setDefault(defSpot->strumaskbl);
     csThresholdblur->setDefault<int>(defSpot->csthresholdblur);
     // Tone Mapping
     stren->setDefault(defSpot->stren);
@@ -6815,6 +6824,7 @@ void Locallab::setDefaults(const rtengine::procparams::ProcParams * defParams, c
         slomaskbl->setDefaultEditedState(Irrelevant);
         lapmaskbl->setDefaultEditedState(Irrelevant);
         shadmaskbl->setDefaultEditedState(Irrelevant);
+        strumaskbl->setDefaultEditedState(Irrelevant);
         csThresholdblur->setDefaultEditedState(Irrelevant);
         // Tone Mapping
         stren->setDefaultEditedState(Irrelevant);
@@ -7014,6 +7024,7 @@ void Locallab::setDefaults(const rtengine::procparams::ProcParams * defParams, c
         slomaskbl->setDefaultEditedState(defSpotState->slomaskbl ? Edited : UnEdited);
         lapmaskbl->setDefaultEditedState(defSpotState->lapmaskbl ? Edited : UnEdited);
         shadmaskbl->setDefaultEditedState(defSpotState->shadmaskbl ? Edited : UnEdited);
+        strumaskbl->setDefaultEditedState(defSpotState->strumaskbl ? Edited : UnEdited);
         csThresholdblur->setDefaultEditedState(defSpotState->csthresholdblur ? Edited : UnEdited);
         // Tone Mapping
         stren->setDefaultEditedState(defSpotState->stren ? Edited : UnEdited);
@@ -7731,6 +7742,12 @@ void Locallab::adjusterChanged(Adjuster * a, double newval)
             }
         }
 
+        if (a == strumaskbl) {
+            if (listener) {
+                listener->panelChanged(Evlocallabstrumaskbl, strumaskbl->getTextValue());
+            }
+        }
+
     }
 
     // Tone Mapping
@@ -8393,6 +8410,7 @@ void Locallab::setBatchMode(bool batchMode)
     slomaskbl->showEditedCB();
     lapmaskbl->showEditedCB();
     shadmaskbl->showEditedCB();
+    strumaskbl->showEditedCB();
     csThresholdblur->showEditedCB();
     // Tone Mapping
     stren->showEditedCB();
@@ -9106,6 +9124,7 @@ void Locallab::updateLocallabGUI(const rtengine::procparams::ProcParams* pp, con
         slomaskbl->setValue(pp->locallab.spots.at(index).slomaskbl);
         lapmaskbl->setValue(pp->locallab.spots.at(index).lapmaskbl);
         shadmaskbl->setValue(pp->locallab.spots.at(index).shadmaskbl);
+        strumaskbl->setValue(pp->locallab.spots.at(index).strumaskbl);
         fftwbl->set_active(pp->locallab.spots.at(index).fftwbl);
         Lmaskblshape->setCurve(pp->locallab.spots.at(index).Lmaskblcurve);
         LLmaskblshapewav->setCurve(pp->locallab.spots.at(index).LLmaskblcurvewav);
@@ -9502,6 +9521,7 @@ void Locallab::updateLocallabGUI(const rtengine::procparams::ProcParams* pp, con
                 slomaskbl->setEditedState(spotState->slomaskbl ? Edited : UnEdited);
                 lapmaskbl->setEditedState(spotState->lapmaskbl ? Edited : UnEdited);
                 shadmaskbl->setEditedState(spotState->shadmaskbl ? Edited : UnEdited);
+                strumaskbl->setEditedState(spotState->strumaskbl ? Edited : UnEdited);
                 fftwbl->set_inconsistent(multiImage && !spotState->fftwbl);
                 Lmaskblshape->setUnChanged(!spotState->Lmaskblcurve);
                 LLmaskblshapewav->setUnChanged(!spotState->LLmaskblcurvewav);
diff --git a/rtgui/locallab.h b/rtgui/locallab.h
index 06481c6f6..4203ce1c9 100644
--- a/rtgui/locallab.h
+++ b/rtgui/locallab.h
@@ -241,6 +241,7 @@ private:
     Adjuster* const isogr;
     Adjuster* const strengr;
     Adjuster* const scalegr;
+    Adjuster* const strumaskbl;
     // Tone Mapping
     Adjuster* const stren;
     Adjuster* const gamma;
diff --git a/rtgui/paramsedited.cc b/rtgui/paramsedited.cc
index 9e0ef2713..1cf336fa2 100644
--- a/rtgui/paramsedited.cc
+++ b/rtgui/paramsedited.cc
@@ -1134,6 +1134,7 @@ void ParamsEdited::initFrom(const std::vector<rtengine::procparams::ProcParams>&
                 locallab.spots.at(j).slomaskbl = locallab.spots.at(j).slomaskbl && pSpot.slomaskbl == otherSpot.slomaskbl;
                 locallab.spots.at(j).lapmaskbl = locallab.spots.at(j).lapmaskbl && pSpot.lapmaskbl == otherSpot.lapmaskbl;
                 locallab.spots.at(j).shadmaskbl = locallab.spots.at(j).shadmaskbl && pSpot.shadmaskbl == otherSpot.shadmaskbl;
+                locallab.spots.at(j).strumaskbl = locallab.spots.at(j).strumaskbl && pSpot.strumaskbl == otherSpot.strumaskbl;
                 locallab.spots.at(j).fftwbl = locallab.spots.at(j).fftwbl && pSpot.fftwbl == otherSpot.fftwbl;
                 locallab.spots.at(j).Lmaskblcurve = locallab.spots.at(j).Lmaskblcurve && pSpot.Lmaskblcurve == otherSpot.Lmaskblcurve;
                 locallab.spots.at(j).LLmaskblcurvewav = locallab.spots.at(j).LLmaskblcurvewav && pSpot.LLmaskblcurvewav == otherSpot.LLmaskblcurvewav;
@@ -3446,6 +3447,10 @@ void ParamsEdited::combine(rtengine::procparams::ProcParams& toEdit, const rteng
             toEdit.locallab.spots.at(i).shadmaskbl = mods.locallab.spots.at(i).shadmaskbl;
         }
 
+        if (locallab.spots.at(i).strumaskbl) {
+            toEdit.locallab.spots.at(i).strumaskbl = mods.locallab.spots.at(i).strumaskbl;
+        }
+
         if (locallab.spots.at(i).Lmaskblcurve) {
             toEdit.locallab.spots.at(i).Lmaskblcurve = mods.locallab.spots.at(i).Lmaskblcurve;
         }
@@ -5086,6 +5091,7 @@ LocallabParamsEdited::LocallabSpotEdited::LocallabSpotEdited(bool v) :
     slomaskbl(v),
     lapmaskbl(v),
     shadmaskbl(v),
+    strumaskbl(v),
     Lmaskblcurve(v),
     LLmaskblcurvewav(v),
     csthresholdblur(v),
@@ -5403,6 +5409,7 @@ void LocallabParamsEdited::LocallabSpotEdited::set(bool v)
     slomaskbl = v;
     lapmaskbl = v;
     shadmaskbl = v;
+    strumaskbl = v;
     Lmaskblcurve = v;
     LLmaskblcurvewav = v;
     csthresholdblur = v;
diff --git a/rtgui/paramsedited.h b/rtgui/paramsedited.h
index 6df4199a0..427e8f130 100644
--- a/rtgui/paramsedited.h
+++ b/rtgui/paramsedited.h
@@ -564,6 +564,7 @@ public:
         bool slomaskbl;
         bool lapmaskbl;
         bool shadmaskbl;
+        bool strumaskbl;
         bool Lmaskblcurve;
         bool LLmaskblcurvewav;
         bool csthresholdblur;