diff --git a/rtengine/iimage.h b/rtengine/iimage.h
index 4362f369a..cd49c1329 100644
--- a/rtengine/iimage.h
+++ b/rtengine/iimage.h
@@ -103,7 +103,7 @@ public:
 template<>
 inline void ImageDatas::convertTo(unsigned short src, unsigned char& dst) const
 {
-    dst = (src + 128) / 257;
+    dst = uint16ToUint8Rounded(src);
 }
 template<>
 inline void ImageDatas::convertTo(unsigned char src, int& dst) const
@@ -118,7 +118,7 @@ inline void ImageDatas::convertTo(unsigned char src, unsigned short& dst) const
 template<>
 inline void ImageDatas::convertTo(float src, unsigned char& dst) const
 {
-    dst = (static_cast<int>(src) + 128) / 257;
+    dst = uint16ToUint8Rounded(src);
 }
 template<>
 inline void ImageDatas::convertTo(unsigned char src, float& dst) const
diff --git a/rtengine/image16.cc b/rtengine/image16.cc
index 11a05902f..b61170e03 100644
--- a/rtengine/image16.cc
+++ b/rtengine/image16.cc
@@ -28,9 +28,9 @@ namespace
 void getScanline8 (const uint16_t *red, const uint16_t *green, const uint16_t *blue, int width, unsigned char* buffer)
 {
     for (int i = 0, ix = 0; i < width; i++) {
-        buffer[ix++] = (red[i] + 128) / 257;
-        buffer[ix++] = (green[i] + 128) / 257;
-        buffer[ix++] = (blue[i] + 128) / 257;
+        buffer[ix++] = rtengine::uint16ToUint8Rounded(red[i]);
+        buffer[ix++] = rtengine::uint16ToUint8Rounded(green[i]);
+        buffer[ix++] = rtengine::uint16ToUint8Rounded(blue[i]);
     }
 }
 
@@ -300,9 +300,9 @@ Image16::to8()
 
     for (int h = 0; h < height; ++h) {
         for (int w = 0; w < width; ++w) {
-            img8->r(h, w) = (r(h, w) + 128) / 257;
-            img8->g(h, w) = (g(h, w) + 128) / 257;
-            img8->b(h, w) = (b(h, w) + 128) / 257;
+            img8->r(h, w) = uint16ToUint8Rounded(r(h, w));
+            img8->g(h, w) = uint16ToUint8Rounded(g(h, w));
+            img8->b(h, w) = uint16ToUint8Rounded(b(h, w));
         }
     }
 
diff --git a/rtengine/image8.cc b/rtengine/image8.cc
index 41589993d..d7a49138b 100644
--- a/rtengine/image8.cc
+++ b/rtengine/image8.cc
@@ -74,7 +74,7 @@ void Image8::setScanline (int row, unsigned char* buffer, int bps, float *minVal
         unsigned short* sbuffer = (unsigned short*) buffer;
 
         for (int i = 0, ix = row * width * 3; i < width * 3; ++i, ++ix) {
-            data[ix] = (sbuffer[i] + 128) / 257;
+            data[ix] = uint16ToUint8Rounded(sbuffer[i]);
         }
 
         break;
diff --git a/rtengine/imagefloat.cc b/rtengine/imagefloat.cc
index 7f84f1cab..ae4a1a09b 100644
--- a/rtengine/imagefloat.cc
+++ b/rtengine/imagefloat.cc
@@ -335,9 +335,9 @@ Imagefloat::to8()
 
     for (int h = 0; h < height; ++h) {
         for (int w = 0; w < width; ++w) {
-            img8->r(h, w) = (static_cast<unsigned int>(r(h, w)) + 128) / 257;
-            img8->g(h, w) = (static_cast<unsigned int>(g(h, w)) + 128) / 257;
-            img8->b(h, w) = (static_cast<unsigned int>(b(h, w)) + 128) / 257;
+            img8->r(h, w) = uint16ToUint8Rounded(r(h, w));
+            img8->g(h, w) = uint16ToUint8Rounded(g(h, w));
+            img8->b(h, w) = uint16ToUint8Rounded(b(h, w));
         }
     }
 
diff --git a/rtengine/iplab2rgb.cc b/rtengine/iplab2rgb.cc
index 419854523..8aff50886 100644
--- a/rtengine/iplab2rgb.cc
+++ b/rtengine/iplab2rgb.cc
@@ -107,9 +107,9 @@ void ImProcFunctions::lab2monitorRgb (LabImage* lab, Image8* image)
 
                 /* copy RGB */
                 //int R1=((int)gamma2curve[(R)])
-                data[ix++] = (static_cast<int>(Color::gamma2curve[R]) + 128) / 257;
-                data[ix++] = (static_cast<int>(Color::gamma2curve[G]) + 128) / 257;
-                data[ix++] = (static_cast<int>(Color::gamma2curve[B]) + 128) / 257;
+                data[ix++] = uint16ToUint8Rounded(Color::gamma2curve[R]);
+                data[ix++] = uint16ToUint8Rounded(Color::gamma2curve[G]);
+                data[ix++] = uint16ToUint8Rounded(Color::gamma2curve[B]);
             }
         }
     }
@@ -218,9 +218,9 @@ Image8* ImProcFunctions::lab2rgb (LabImage* lab, int cx, int cy, int cw, int ch,
 
                 Color::xyz2rgb(x_, y_, z_, R, G, B, xyz_rgb);
 
-                image->data[ix++] = (static_cast<int>(Color::gamma2curve[R]) + 128) / 257;
-                image->data[ix++] = (static_cast<int>(Color::gamma2curve[G]) + 128) / 257;
-                image->data[ix++] = (static_cast<int>(Color::gamma2curve[B]) + 128) / 257;
+                image->data[ix++] = uint16ToUint8Rounded(Color::gamma2curve[R]);
+                image->data[ix++] = uint16ToUint8Rounded(Color::gamma2curve[G]);
+                image->data[ix++] = uint16ToUint8Rounded(Color::gamma2curve[B]);
             }
         }
     }
diff --git a/rtengine/rt_math.h b/rtengine/rt_math.h
index f55f7c1b2..67d883080 100644
--- a/rtengine/rt_math.h
+++ b/rtengine/rt_math.h
@@ -1,14 +1,15 @@
-#ifndef _MYMATH_
-#define _MYMATH_
-#include <cmath>
-#include <algorithm>
+#pragma once
 
+#include <algorithm>
+#include <cmath>
+#include <cstdint>
 
 namespace rtengine
 {
-static const int MAXVAL = 0xffff;
-static const float MAXVALF = float(MAXVAL);  // float version of MAXVAL
-static const double MAXVALD = double(MAXVAL); // double version of MAXVAL
+
+constexpr int MAXVAL = 0xffff;
+constexpr float MAXVALF = static_cast<float>(MAXVAL);  // float version of MAXVAL
+constexpr double MAXVALD = static_cast<double>(MAXVAL); // double version of MAXVAL
 
 template <typename _Tp>
 inline _Tp SQR (_Tp x)
@@ -107,6 +108,9 @@ inline int float2uint16range(float d) // clips input to [0;65535] and rounds
     return d + 0.5f;
 }
 
+constexpr std::uint8_t uint16ToUint8Rounded(std::uint16_t i)
+{
+    return ((i + 128) - ((i + 128) >> 8)) >> 8;
 }
 
-#endif
+}