diff --git a/CMakeModules/CheckAtomicOps.cmake b/CMakeModules/CheckAtomicOps.cmake
index 71c7eb788..3cd1876d8 100644
--- a/CMakeModules/CheckAtomicOps.cmake
+++ b/CMakeModules/CheckAtomicOps.cmake
@@ -77,6 +77,7 @@ int main(int, const char**)
    long* volatile ptr = &data;
 
    InterlockedIncrement(&value);
+   MemoryBarrier();
    InterlockedDecrement(&value);
 
    if (0 != InterlockedCompareExchange(&value, 1, 0))
diff --git a/src/osg/Image.cpp b/src/osg/Image.cpp
index d410345bc..9dc9f61c8 100644
--- a/src/osg/Image.cpp
+++ b/src/osg/Image.cpp
@@ -553,7 +553,10 @@ void Image::allocateImage(int s,int t,int r,
         _pixelFormat = format;
         _dataType = type;
         _packing = packing;
-        _internalTextureFormat = format;
+        
+        // preserve internalTextureFormat if already set, otherwise
+        // use the pixelFormat as the source for the format.
+        if (_internalTextureFormat==0) _internalTextureFormat = format;
     }
     else
     {
@@ -565,7 +568,10 @@ void Image::allocateImage(int s,int t,int r,
         _pixelFormat = 0;
         _dataType = 0;
         _packing = 0;
-        _internalTextureFormat = 0;
+        
+        // commenting out reset of _internalTextureFormat as we are changing
+        // policy so that allocateImage honours previous settings of _internalTextureFormat.
+        //_internalTextureFormat = 0;
     }
     
     dirty();