private void button1_Click(object sender, EventArgs e)
{
    var service = new PicasaService("exampleCo-exampleApp-1");
    service.setUserCredentials("me.myself@gmail.com", "-secret-");
    AlbumQuery query = new AlbumQuery(PicasaQuery.CreatePicasaUri("default"));


    PicasaFeed feed = service.Query(query);
    var entry = (PicasaEntry)feed.Entries.SingleOrDefault(f => f.Title.Text == "Testalbum");

    var ac = new AlbumAccessor(entry);

    var photoQuery = new PhotoQuery(PicasaQuery.CreatePicasaUri("default", ac.Id));
    PicasaFeed photoFeed = service.Query(photoQuery);

    DirectoryInfo srcdir = Directory.CreateDirectory("C:\\Temp\\Testalbum");
    DownloadAllPhotos("C:\\Temp\\Testalbum", photoFeed.Entries);

    foreach (PicasaEntry oldentry in photoFeed.Entries)
    {
        oldentry.Delete();
    }

    DirectoryInfo tgtdir = Directory.CreateDirectory("C:\\Temp\\Converted");
    foreach (FileInfo imagefile in srcdir.EnumerateFiles())
    {
        Image img = Image.FromFile(imagefile.FullName);

        PropertyItem PiDtOrig = null;
        try
        {
            PiDtOrig = img.GetPropertyItem(0x9003); // id 0x9003 is "DateTimeOriginal"
        }
        catch (System.ArgumentException ex) // this exception is thrown when PropertyItem does not exist 
        {
            PiDtOrig = NewPropertyItem();
            PiDtOrig.Id = 0x9003;
            PiDtOrig.Type = 7;
            PiDtOrig.Len = 4;
        }

        PiDtOrig.Value = BitConverter.GetBytes(DateTimeToInt(DateTime.Now));
        img.SetPropertyItem(PiDtOrig);
        string ConvImgName = tgtdir.FullName + "\\" + imagefile.Name;
        img.Save(ConvImgName);

        //ExifTagCollection exif = new ExifTagCollection(img);
        //Debug.WriteLine(exif);

        Uri postUri = new Uri(PicasaQuery.CreatePicasaUri("hommel.peter@gmail.com", ac.Id));
        FileStream fileStream = imagefile.OpenRead();

        PicasaEntry newentry = (PicasaEntry)service.Insert(postUri, fileStream, "image/jpeg", ConvImgName);

        fileStream.Close();
        fileStream.Dispose();
    }
}

private PropertyItem NewPropertyItem()
{
    Type t = typeof (PropertyItem);
    ConstructorInfo ctor = t.GetConstructors(BindingFlags.Instance | BindingFlags.NonPublic)[0];
    Object o = ctor.Invoke(new Object[] { });
    return (PropertyItem) o;
}

private int DateTimeToInt(DateTime theDate)
{
    return (int)(theDate.Date - new DateTime(1900, 1, 1)).TotalDays + 2;
}

// taken from https://codethis.wordpress.com/2008/11/ and modified for this example
static void DownloadAllPhotos(string DirectoryName, AtomEntryCollection photoList)
{
    DirectoryInfo dirInfo = Directory.CreateDirectory(DirectoryName);

    int photoNum = 1;
    foreach (AtomEntry photo in photoList)
    {
        HttpWebRequest photoRequest = WebRequest.Create(photo.Content.AbsoluteUri) as HttpWebRequest;
        HttpWebResponse photoResponse = photoRequest.GetResponse() as
           HttpWebResponse;

        BufferedStream bufferedStream = new BufferedStream(
           photoResponse.GetResponseStream(), 1024);
        BinaryReader reader = new BinaryReader(bufferedStream);

        FileStream imgOut = File.Create(dirInfo.FullName + "\\image" +
           photoNum++ + ".jpg");
        BinaryWriter writer = new BinaryWriter(imgOut);

        int bytesRead = 1;
        byte[] buffer = new byte[1024];
        while (bytesRead > 0)
        {
            bytesRead = reader.Read(buffer, 0, buffer.Length);
            writer.Write(buffer, 0, bytesRead);
        }
        reader.Close();
        reader.Dispose();
        writer.Flush();
        writer.Close();
        writer.Dispose();
    }
}

请容忍我发布了一些脏代码，但我很快就把它拼凑在一起了。

你会在上面的代码中找到两行注释掉的代码，它们使用了我前段时间在网上找到的一些 Exif 类。由于他们直接在这里公开了太多代码，我已经将它们上传到 Pastebin:

http://pastebin.com/pkZMVZ9i

虽然它们只允许读取 Exif，但在您尝试为其他 Exif 标签找到合适的 PropertyItem 内容时，它们仍然对您有用。

因为我不知道这段代码是从哪里来的，如果有人知道，请写评论，这样我也可以在这里添加这些信息。