diff --git a/client/renderSDL/SDL_Extensions.cpp b/client/renderSDL/SDL_Extensions.cpp
index 33c36e21e..406b7f5c7 100644
--- a/client/renderSDL/SDL_Extensions.cpp
+++ b/client/renderSDL/SDL_Extensions.cpp
@@ -543,7 +543,7 @@ void CSDL_Ext::putPixelWithoutRefreshIfInSurf(SDL_Surface *ekran, const int & x,
 }
 
 template<int bpp>
-void CSDL_Ext::convertToGrayscaleBpp(SDL_Surface * surf, const Rect & rect )
+void loopOverPixel(SDL_Surface * surf, const Rect & rect, std::function<void(int &r, int &g, int &b)> func)
 {
 	uint8_t * pixels = static_cast<uint8_t*>(surf->pixels);
 
@@ -560,16 +560,27 @@ void CSDL_Ext::convertToGrayscaleBpp(SDL_Surface * surf, const Rect & rect )
 				int g = Channels::px<bpp>::g.get(pixel);
 				int b = Channels::px<bpp>::b.get(pixel);
 
-				int gray = static_cast<int>(0.299 * r + 0.587 * g + 0.114 *b);
+				func(r, g, b);
 
-				Channels::px<bpp>::r.set(pixel, gray);
-				Channels::px<bpp>::g.set(pixel, gray);
-				Channels::px<bpp>::b.set(pixel, gray);
+				Channels::px<bpp>::r.set(pixel, r);
+				Channels::px<bpp>::g.set(pixel, g);
+				Channels::px<bpp>::b.set(pixel, b);
 			}
 		}
 	});
 }
 
+template<int bpp>
+void CSDL_Ext::convertToGrayscaleBpp(SDL_Surface * surf, const Rect & rect )
+{
+	loopOverPixel<bpp>(surf, rect, [](int &r, int &g, int &b){
+		int gray = static_cast<int>(0.299 * r + 0.587 * g + 0.114 * b);
+		r = gray;
+		g = gray;
+		b = gray;
+	});
+}
+
 void CSDL_Ext::convertToGrayscale( SDL_Surface * surf, const Rect & rect )
 {
 	switch(surf->format->BytesPerPixel)
@@ -582,38 +593,18 @@ void CSDL_Ext::convertToGrayscale( SDL_Surface * surf, const Rect & rect )
 template<int bpp>
 void CSDL_Ext::convertToH2SchemeBpp(SDL_Surface * surf, const Rect & rect )
 {
-	uint8_t * pixels = static_cast<uint8_t*>(surf->pixels);
+	loopOverPixel<bpp>(surf, rect, [](int &r, int &g, int &b){
+		double gray = 0.3 * r + 0.59 * g + 0.11 * b;
+		double factor = 2.0;
 
-	tbb::parallel_for(tbb::blocked_range<size_t>(rect.top(), rect.bottom()), [&](const tbb::blocked_range<size_t>& r)
-	{
-		for(int yp = r.begin(); yp != r.end(); ++yp)
-		{
-			uint8_t * pixel_from = pixels + yp * surf->pitch + rect.left() * surf->format->BytesPerPixel;
-			uint8_t * pixel_dest = pixels + yp * surf->pitch + rect.right() * surf->format->BytesPerPixel;
+		//fast approximation instead of colorspace conversion
+		r = static_cast<int>(gray + (r - gray) * factor);
+		g = static_cast<int>(gray + (g - gray) * factor);
+		b = static_cast<int>(gray + (b - gray) * factor);
 
-			for (uint8_t * pixel = pixel_from; pixel < pixel_dest; pixel += surf->format->BytesPerPixel)
-			{
-				int r = Channels::px<bpp>::r.get(pixel);
-				int g = Channels::px<bpp>::g.get(pixel);
-				int b = Channels::px<bpp>::b.get(pixel);
-
-				double gray = 0.3 * r + 0.59 * g + 0.11 * b;
-				double factor = 2.0;
-
-				//fast approximation instead of colorspace conversion
-				r = static_cast<int>(gray + (r - gray) * factor);
-				g = static_cast<int>(gray + (g - gray) * factor);
-				b = static_cast<int>(gray + (b - gray) * factor);
-
-				r = std::clamp(r, 0, 255);
-				g = std::clamp(g, 0, 255);
-				b = std::clamp(b, 0, 255);
-
-				Channels::px<bpp>::r.set(pixel, r);
-				Channels::px<bpp>::g.set(pixel, g);
-				Channels::px<bpp>::b.set(pixel, b);
-			}
-		}
+		r = std::clamp(r, 0, 255);
+		g = std::clamp(g, 0, 255);
+		b = std::clamp(b, 0, 255);
 	});
 }