title: Changing "DateTaken" of a photo
body: <p>I just came back from a trip to the US, and after editing all the photos, I noticed that the camera used the Israeli time zone, and not the american. There is a 7 hours time difference, so it's a big problem for me. I have 175GB of photos, but I care "only" about 350 photos. I can't edit their EXIF manually, so I thought about using C#. </p>
  
  <p>The idea is that it will read each photo's EXIF, get the time, and set the time minus 7 hours in the original photo. I tried using the Image class, but it doesn't work. I tried using the bitmapMetadate, and it worked! I've managed to get the time and do minus seven hours, but I have no idea how to save it. How can I do it? Thanks!</p>
  
  <pre><code>    public static string PhotoToBeEdited(FileInfo f)
      {
          FileStream fs = new FileStream(f.FullName, FileMode.Open, FileAccess.Read, FileShare.Read);
          BitmapSource img = BitmapFrame.Create(fs);
          BitmapMetadata md = (BitmapMetadata)img.Metadata;
          string date = md.DateTaken;
          Console.WriteLine(date);
          DateTime dt= DateTime.Parse(date);
          date = dt.AddHours(-7).ToString();
  
          [...]
  
          return date;
      }
  </code></pre>