Hi, I must confess I am not an expert on graphic images. I'm not surprised that you are not experiencing any difference with these two lines of codes though. AntiAlias is used in graphics applications for the smoothing of text and lines (diagonals and circles for example) and to help reduce wavy lines, bands or moiré patterns in images  HighQualityBicubic is an algorithm used when scaling images (Shrink or Stretch) to maintain reasonable image quality with respect to the original image. So depending on your original images these lines of code may or may not have an effect on the resized image quality. I leave them in just in case. Take a look at

http://msdn2.microsoft.com/en-us/library/a619zh6z.aspx

 http://msdn2.microsoft.com/en-us/library/k0fsyd4e(VS.85).aspx

Hope this helps answer your questions.