ImageBrush中的图片如何加载到到MemoryStream

            ImageBrush ib = new ImageBrush();
            Bitmap bitmap;
            ib.ImageSource = image1.Source;
            BitmapEncoder encoder = new PngBitmapEncoder();
            //PngBitmapEncoder encoder = new PngBitmapEncoder();
            encoder.Frames.Add(BitmapFrame.Create(ib.ImageSource as BitmapSource));
            encoder.Save(ms);

            ms.Flush();

相反的情况，从 MemoryStream加载图片到ImageBrush

                ImageBrush imageBrush = new ImageBrush();
                ImageSourceConverter imageSourceConverter = new ImageSourceConverter();
                imageBrush.ImageSource = (ImageSource)imageSourceConverter.ConvertFrom(stream);

                image1.Source = imageBrush.ImageSource;

以上stream是一个MemoryStream