JpegBitmapEncoder leaves gray streak at end of fil

Question

I'm working with the WPF imaging components in an attempt to do some simple image manipulation. I'm roughly following the MS article on How to Encode & Decode a JPEG Image.

My code is simple:

BitmapImage bi = new BitmapImage();

bi.BeginInit();
bi.UriSource = new Uri("D:\\Temp\\StackOverflowCapture.png");
//bi.DecodePixelWidth = 1024;
//bi.DecodePixelHeight = 768;
bi.EndInit();

var jpg                  = new JpegBitmapEncoder();
    jpg.QualityLevel     = 90;
    //jpg.FlipHorizontal = false;
    //jpg.FlipVertical   = false;
    jpg.Frames.Add(BitmapFrame.Create(bi));

var fs = new FileStream("D:\\Temp\\StackOverflow_Result.jpg", FileMode.Create);

jpg.Save( fs );
jpg = null;

The code snippet creates an odd artifact, where the last few "lines" are a block of solid gray. It's almost as if the encoder just ran out of pixels to write. The amount of gray varies by a factor of 2x or 3x depending on the image I use as input (various resolutions, jpeg, png) or the options I enable (forcing resolution on decode). The net effect is the same, however, as you can see from the images below.

My source image is :

Output image ( note the gray band at the bottom):

What's going on here? How do I get a clean convert?

Answer 1

This was definitely a short circuit between the ears. For the sake of others with similar frailties, however, I'm answering my own question.

You need to close/flush the stream. Alternately, it would be good practice to create fs in a using block.

Modified code is thus:

BitmapImage bi = new BitmapImage();

bi.BeginInit();
bi.UriSource = new Uri("D:\\Temp\\StackOverflow_Source.png");
bi.EndInit();

var jpg                  = new JpegBitmapEncoder();
    jpg.QualityLevel     = 90;
    jpg.Frames.Add(BitmapFrame.Create(bi));

var fs = new FileStream("D:\\Temp\\StackOverflow_Result.jpg", FileMode.Create);

jpg.Save( fs );
fs.close();       <--- duh, flush the stream to disk
jpg = null;