BmpBitmapEncoder lock files on disk after reading Bitmap from file

System.Windows.Controls.Image imageControl = ....

BmpBitmapEncoder bmpBitmapEncoder =newBmpBitmapEncoder();

BitmapFrame bitmapFrame =BitmapFrame.Create(imageControl.SourceasBitmapSource);

bmpBitmapEncoder.Frames.Add(bitmapFrame);

MemoryStream stream =newMemoryStream();

using (FileStream fs =File.Create("t:\\out.bmp"))

{

bmpBitmapEncoder.Save(fs);

}

So, after ".Save(fs)" original bitmap file (c:\imageShape.bmp) is locked and I can't delete it until I close the process. How can I unlock this file?