fixed many warnings from GCC 4.6.1

modules/highgui/src/loadsave.cpp

@@ -399,8 +399,7 @@ Mat imdecode( InputArray _buf, int flags )
 bool imencode( const string& ext, InputArray _image,
                vector<uchar>& buf, const vector<int>& params )
 {
-    Mat temp, image = _image.getMat();
-    const Mat* pimage = &image;
+    Mat image = _image.getMat();
 
     int channels = image.channels();
     CV_Assert( channels == 1 || channels == 3 || channels == 4 );
@@ -412,8 +411,9 @@ bool imencode( const string& ext, InputArray _image,
     if( !encoder->isFormatSupported(image.depth()) )
     {
         CV_Assert( encoder->isFormatSupported(CV_8U) );
+        Mat temp;
         image.convertTo(temp, CV_8U);
-        pimage = &temp;
+        image = temp;
     }
 
     bool code;

modules/highgui/src/window_gtk.cpp

@@ -156,7 +156,6 @@ cvImageWidgetNew (int flags)
 static void
 cvImageWidget_realize (GtkWidget *widget)
 {
-  CvImageWidget *image_widget;
   GdkWindowAttr attributes;
   gint attributes_mask;
 
@@ -165,7 +164,6 @@ cvImageWidget_realize (GtkWidget *widget)
   g_return_if_fail (CV_IS_IMAGE_WIDGET (widget));
 
   GTK_WIDGET_SET_FLAGS (widget, GTK_REALIZED);
-  image_widget = CV_IMAGE_WIDGET (widget);
 
   attributes.x = widget->allocation.x;
   attributes.y = widget->allocation.y;

modules/highgui/test/test_grfmt.cpp

@@ -88,7 +88,6 @@ public:
         {
             const int img_r = 640;
             const int img_c = 480;
-            Size frame_s = Size(img_c, img_r);
 
             for (int k = 1; k <= 5; ++k)
             {

modules/highgui/test/test_video_io.cpp

@@ -230,7 +230,6 @@ void CV_HighGuiTest::VideoTest(const string& dir, int fourcc)
 
     CvVideoWriter* writer = 0;
 
-    int counter = 0;
     for(;;)
     {
         IplImage * img = cvQueryFrame( cap );
@@ -267,7 +266,6 @@ void CV_HighGuiTest::VideoTest(const string& dir, int fourcc)
 
     const double thresDbell = 20;
 
-    counter = 0;
     for(;;)
     {
         IplImage* ipl  = cvQueryFrame( cap );