Garbage collection fails to reclaim BitmapImage?

Question

I have an application(WPF) which creates BitmapImages in huge numbers(like 25000). Seems like framework uses some internal logic so after creation there are approx 300 mb of

Answer 1

I am just telling my experience about reclaiming BitmapImage memory. I work with .Net Framework 4.5.
I create simple WPF Application and Load a large image file. I tried to clear Image from memory using following code:

private void ButtonImageRemove_Click(object sender, RoutedEventArgs e)
    {

        image1.Source = null;
        GC.Collect();
    }

But It didn't work. I tried other solutions too , but I didn't get my answer. After a few days struggling, I found out if I press the button twice, GC will free the memory. then I simply write this code to call GC collector a few second after clicking the button .

private void ButtonImageRemove_Click(object sender, RoutedEventArgs e)
    {

        image1.Source = null;
        System.Threading.Thread thread = new System.Threading.Thread(new System.Threading.ThreadStart(delegate
        {
            System.Threading.Thread.Sleep(500);
            GC.Collect();
        }));
        thread.Start();

    }

this code just tested in DotNetFr 4.5. maybe you have to freeze BitmapImage object for lower .Net Framework .
Edit
This Code doesn't work unless layout get updated. I mean if parent control get removed, GC fails to reclaim it.