diff --git a/include/osg/Image b/include/osg/Image
index 062de484c..b8c4f5f33 100644
--- a/include/osg/Image
+++ b/include/osg/Image
@@ -131,7 +131,6 @@ class OSG_EXPORT Image : public Object
         */
         void copySubImage(int s_offset,int t_offset,int r_offset,osg::Image* source);
 
-
         /** Width of image. */
         inline int s() const { return _s; }
 
@@ -166,6 +165,9 @@ class OSG_EXPORT Image : public Object
         /** Return the number of bytes the whole row/image/volume of pixels occupies, including all mip maps if included. */
         unsigned int getTotalSizeInBytesIncludingMipmaps() const;
 
+        /** Return true if the Image represent a valid and usable imagery.*/
+        bool valid() const { return _s!=0 && _t!=0 && _r!=0 && _data!=0 && _dataType!=0; }
+
         /** Raw image data. */
         inline unsigned char *data() { return _data; }
         
diff --git a/src/osg/BufferObject.cpp b/src/osg/BufferObject.cpp
index b1dd08e6c..51accb847 100644
--- a/src/osg/BufferObject.cpp
+++ b/src/osg/BufferObject.cpp
@@ -323,23 +323,28 @@ void PixelBufferObject::compileBuffer(State& state) const
     unsigned int contextID = state.getContextID();
     if (!needsCompile(contextID)) return;
     
-    Extensions* extensions = getExtensions(contextID,true);
-
     osg::Image* image = _bufferEntryImagePair.second;
-    
+
+    _bufferEntryImagePair.first.modifiedCount[contextID] = image->getModifiedCount();
+    if (!image->valid()) return;
+
+    Extensions* extensions = getExtensions(contextID,true);
 
     GLuint& pbo = buffer(contextID);
     if (pbo==0)
     {
         // building for the first time.
-        extensions->glGenBuffers(1, &pbo);
-
-        extensions->glBindBuffer(_target, pbo);
 
         _totalSize = image->getTotalSizeInBytes();
 
+        // don't generate buffer if size is zero.        
+        if (_totalSize==0) return;
+
+        extensions->glGenBuffers(1, &pbo);
+        extensions->glBindBuffer(_target, pbo);
         extensions->glBufferData(_target, _totalSize, NULL,
                      _usage);
+                    
     }
     else
     {
@@ -347,6 +352,7 @@ void PixelBufferObject::compileBuffer(State& state) const
 
         if (_totalSize != image->getTotalSizeInBytes())
         {
+
             _totalSize = image->getTotalSizeInBytes();
             extensions->glBufferData(_target, _totalSize, NULL,
                      _usage);