将位图压缩为JPG格式

如何将将位图压缩为JPG格式?有范例吗?

public static byte[] CompressBitmapToJpg(System.Drawing.Bitmap bm)
{
MemoryStream memStream = new MemoryStream();
bm.Save(memStream, System.Drawing.Imaging.ImageFormat.Jpeg);
byte[] bResult = memStream.ToArray();
memStream.Close();

return bResult;
}