make sure we get images in the format we need them to be in; fixes issues on 16bit displays

svn path=/trunk/KDE/kdelibs/; revision=1023999

private/effects/blur.cpp

@@ -50,10 +50,12 @@ static inline void blurcol(QImage &im, int col, int alpha);
 template<int aprec,int zprec>
 void expblur(QImage &img, int radius)
 {
-    if(radius < 1) {
+  if (radius < 1) {
     return;
   }
 
+  img = img.convertToFormat(QImage::Format_ARGB32_Premultiplied);
+
   /* Calculate the alpha such that 90% of
      the kernel is within the radius.
      (Kernel extends to infinity)