Why after calling dispose on bitmap object GDI objects are not getting released immediately

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.NET

unmanaged

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I am creating a Bitmap object and from that Bitmap object creating an Icon and then Disposing them accordingly. While running the code I collected GDI object count after each GDI operation. Observed that after calling Dispose on the Bitmap object, GDI object count is still same.

class Icon_ResouceLeak
 {
     static void Main(string[] args)
     {
         // the program starts with 18 GDI objects..

         var bmp = new Bitmap("imagePath");
         // 25 GDI objects..

         IntPtr ptr = bmp.GetHicon();
         // 30 GDI Objects..

         Icon newIcon = Icon.FromHandle(ptr);

         var clonedIcon = (Icon)newIcon.Clone();
         // 33 GDI objects..

         DestroyIcon(newIcon.Handle);
         // 30 GDI objects ..

         clonedIcon.Dispose();
         // 27 GDI objects ..

         newIcon.Dispose();
         // 27 GDI objects..

         bmp.Dispose();
         // still 27 GDI objects? 
     }

     [DllImport("user32.dll", CharSet = CharSet.Auto)]
     extern static bool DestroyIcon(IntPtr handle);
 }

What I have tried:


bmp.Dispose() calls Image.Dispsoe(). Which internally calls, SafeNativeMethods.Gdip.GdipDisposeImage(new HandleRef(this, nativeImage));
if this is the case then why it is not released.