how to set Camera Capture Task WP7 properties

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C#

.NET

Windows-Phone-7

Hello, i Try build application windows phone 7, but i have little problem in capture image with the camera.

private void button1_Click(object sender, RoutedEventArgs e)
       {
           CameraCaptureTask task = new CameraCaptureTask();
           task.Completed += (s, evt) =>
           {
               if (evt.Error == null && evt.TaskResult == TaskResult.OK)
               {
                   bmpImage.SetSource(evt.ChosenPhoto);
                   image1.Source = bmpImage;
               }
           };
           task.Show();
       }

this code above work 100% but I need to fix size 320*240 pixel image while capture.
any body know the properties to set it?