I have a fair few images that I'm loading into a ListBox in my WPF application. Originally I was using GDI to resize the images (the originals take up far too much memory). That was fine, except they were taking about 400ms per image. Not so fine. So in search of another solution I found a method that uses TransformedBitmap (which inherits from BitmapSource). That's great, I thought, I can use that. Except I'm now getting memory leaks somewhere...

I'm loading the images asynchronously using a BackgroundWorker like so:

BitmapSource bs = ImageUtils.ResizeBitmapSource(ImageUtils.GetImageSource(photo.FullName));
                //BitmapSource bs = ImageUtils.GetImageSource(photo.FullName);
                bs.Freeze();

                this.dispatcher.Invoke(new Action(() => { photo.Source = bs; }));

GetImageSource just gets the Bitmap from the path and then converts to BitmapSource.

Here's the code snippet for ResizeBitmapSource:

const int thumbnailSize = 200;
        int width;
        int height;

        if (bs.Width > bs.Height)
        {
            width = thumbnailSize;
            height = (int)(bs.Height * thumbnailSize / bs.Width);
        }
        else
        {
            height = thumbnailSize;
            width = (int)(bs.Width * thumbnailSize / bs.Height);
        }

        BitmapSource tbBitmap = new TransformedBitmap(bs,
                                                           new ScaleTransform(width / bs.Width,
                                                                              height / bs.Height, 0, 0));

        return tbBitmap;

That code is essentially the code from: http://rongchaua.net/blog/c-wpf-fast-image-resize/

Any ideas what could be causing the leak?