started work on making RT not clip the image at intermediate stages

rtengine/rt_math.h

@@ -137,4 +137,20 @@ constexpr std::uint8_t uint16ToUint8Rounded(std::uint16_t i)
     return ((i + 128) - ((i + 128) >> 8)) >> 8;
 }
 
+
+template <typename T>
+constexpr bool OOG(const T &val, const T &high=T(MAXVAL))
+{
+    return (val > high);
+}
+
+template <typename T>
+void setUnlessOOG(T &out, const T &val)
+{
+    if (!OOG(out)) {
+        out = val;
+    }
+}
+
+
 }