diff --git a/libs/pigment/compositeops/KoCompositeOpAlphaDarken.h b/libs/pigment/compositeops/KoCompositeOpAlphaDarken.h
--- a/libs/pigment/compositeops/KoCompositeOpAlphaDarken.h
+++ b/libs/pigment/compositeops/KoCompositeOpAlphaDarken.h
@@ -57,7 +57,7 @@
 
         qint32        srcInc       = (params.srcRowStride == 0) ? 0 : channels_nb;
         channels_type flow         = scale<channels_type>(params.flow);
-        channels_type opacity      = mul(flow, scale<channels_type>(params.opacity));
+        channels_type opacity      = scale<channels_type>(params.opacity);
         quint8*       dstRowStart  = params.dstRowStart;
         const quint8* srcRowStart  = params.srcRowStart;
         const quint8* maskRowStart = params.maskRowStart;
@@ -89,7 +89,7 @@
 
                 if(alpha_pos != -1) {
                     channels_type fullFlowAlpha;
-                    channels_type averageOpacity = mul(flow, scale<channels_type>(*params.lastOpacity));
+                    channels_type averageOpacity = scale<channels_type>(*params.lastOpacity);
 
                     if (averageOpacity > opacity) {
                         channels_type reverseBlend = KoColorSpaceMaths<channels_type>::divide(dstAlpha, averageOpacity);
@@ -101,8 +101,10 @@
                     if (params.flow == 1.0) {
                         dstAlpha = fullFlowAlpha;
                     } else {
-                        channels_type zeroFlowAlpha = unionShapeOpacity(srcAlpha, dstAlpha);
+                        channels_type zeroFlowAlpha = dstAlpha;
                         dstAlpha = lerp(zeroFlowAlpha, fullFlowAlpha, flow);
+
+
                     }
 
                     dst[alpha_pos] = dstAlpha;
diff --git a/libs/pigment/compositeops/KoOptimizedCompositeOpAlphaDarken128.h b/libs/pigment/compositeops/KoOptimizedCompositeOpAlphaDarken128.h
--- a/libs/pigment/compositeops/KoOptimizedCompositeOpAlphaDarken128.h
+++ b/libs/pigment/compositeops/KoOptimizedCompositeOpAlphaDarken128.h
@@ -29,13 +29,11 @@
     struct OptionalParams {
         OptionalParams(const KoCompositeOp::ParameterInfo& params)
         : flow(params.flow)
-        , averageOpacity(*params.lastOpacity * params.flow)
-        , premultipliedOpacity(params.opacity * params.flow)
+        , averageOpacity(*params.lastOpacity)
         {
         }
         float flow;
         float averageOpacity;
-        float premultipliedOpacity;
     };
 
     struct Pixel {
@@ -83,12 +81,7 @@
             msk_norm_alpha = src_alpha;
         }
 
-        // we don't use directly passed value
-        Q_UNUSED(opacity);
-
-        // instead we should use opacity premultiplied by flow
-        opacity = oparams.premultipliedOpacity;
-        Vc::float_v opacity_vec(oparams.premultipliedOpacity);
+        Vc::float_v opacity_vec(opacity);
 
         src_alpha = msk_norm_alpha * opacity_vec;
 
@@ -142,7 +135,7 @@
             dst_alpha = fullFlowAlpha;
         }
         else {
-            Vc::float_v zeroFlowAlpha = src_alpha + dst_alpha - src_alpha * dst_alpha;
+            Vc::float_v zeroFlowAlpha = dst_alpha;
             Vc::float_v flow_norm_vec(oparams.flow);
             dst_alpha = (fullFlowAlpha - zeroFlowAlpha) * flow_norm_vec + zeroFlowAlpha;
         }
@@ -166,9 +159,6 @@
         const float uint8Rec1 = 1.0 / 255.0;
         float mskAlphaNorm = haveMask ? float(*mask) * uint8Rec1 * src[alpha_pos] : src[alpha_pos];
 
-        Q_UNUSED(opacity);
-        opacity = oparams.premultipliedOpacity;
-
         float srcAlphaNorm = mskAlphaNorm * opacity;
 
         if (dstAlphaNorm != 0) {
@@ -195,7 +185,7 @@
         if (flow == 1.0) {
             dst[alpha_pos] = fullFlowAlpha;
         } else {
-            float zeroFlowAlpha = unionShapeOpacity(srcAlphaNorm, dstAlphaNorm);
+            float zeroFlowAlpha = dstAlphaNorm;
             dst[alpha_pos] = lerp(zeroFlowAlpha, fullFlowAlpha, flow);
         }
     }
diff --git a/libs/pigment/compositeops/KoOptimizedCompositeOpAlphaDarken32.h b/libs/pigment/compositeops/KoOptimizedCompositeOpAlphaDarken32.h
--- a/libs/pigment/compositeops/KoOptimizedCompositeOpAlphaDarken32.h
+++ b/libs/pigment/compositeops/KoOptimizedCompositeOpAlphaDarken32.h
@@ -31,13 +31,11 @@
     struct OptionalParams {
         OptionalParams(const KoCompositeOp::ParameterInfo& params)
             : flow(params.flow),
-              averageOpacity(*params.lastOpacity * params.flow),
-              premultipliedOpacity(params.opacity * params.flow)
+              averageOpacity(*params.lastOpacity)
         {
         }
         float flow;
         float averageOpacity;
-        float premultipliedOpacity;
     };
 
     /**
@@ -59,12 +57,7 @@
         Vc::float_v src_alpha;
         Vc::float_v dst_alpha;
 
-        // we don't use directly passed value
-        Q_UNUSED(opacity);
-
-        // instead we should use opacity premultiplied by flow
-        opacity = oparams.premultipliedOpacity;
-        Vc::float_v opacity_vec(255.0 * oparams.premultipliedOpacity);
+        Vc::float_v opacity_vec(255.0 * opacity);
 
         Vc::float_v average_opacity_vec(255.0 * oparams.averageOpacity);
         Vc::float_v flow_norm_vec(oparams.flow);
@@ -170,8 +163,7 @@
         if (oparams.flow == 1.0) {
             dst_alpha = fullFlowAlpha;
         } else {
-            Vc::float_v zeroFlowAlpha = src_alpha + dst_alpha -
-                dst_blend * dst_alpha;
+            Vc::float_v zeroFlowAlpha = dst_alpha;
             dst_alpha = (fullFlowAlpha - zeroFlowAlpha) * flow_norm_vec + zeroFlowAlpha;
         }
 
@@ -196,9 +188,6 @@
         float srcAlphaNorm;
         float mskAlphaNorm;
 
-        Q_UNUSED(opacity);
-        opacity = oparams.premultipliedOpacity;
-
         if (haveMask) {
             mskAlphaNorm = float(*mask) * uint8Rec2 * src[alpha_pos];
             srcAlphaNorm = mskAlphaNorm * opacity;
@@ -234,7 +223,7 @@
         if (flow == 1.0) {
             dstAlpha = fullFlowAlpha * uint8Max;
         } else {
-            float zeroFlowAlpha = unionShapeOpacity(srcAlphaNorm, dstAlphaNorm);
+            float zeroFlowAlpha = dstAlphaNorm;
             dstAlpha = lerp(zeroFlowAlpha, fullFlowAlpha, flow) * uint8Max;
         }