Reading "People Tags" inserted by Windows Live Photo Gallery

Question

Photo Gallery gives you the ability to mark a person's face and apply a tag to it. I understand it inserts tags directly into the file rather than store it off in a database or accompanying metafile anywhere.

So if that's true, what data is it inserting and how is it formatted?

Jamesjamesian

Answer 1

Here's the code I wanted. It's in C#.

        public void ReadWLPGRegions(string sourceFile)
    {
        string microsoftRegions = @"/xmp/RegionInfo/Regions";
        string microsoftPersonDisplayName = @"/PersonDisplayName";
        string microsoftRectangle = @"/Rectangle";
        BitmapCreateOptions createOptions = BitmapCreateOptions.PreservePixelFormat | BitmapCreateOptions.IgnoreColorProfile;

        using (Stream sourceStream = File.Open(sourceFile, FileMode.Open, FileAccess.Read))
        {
            BitmapDecoder sourceDecoder = BitmapDecoder.Create(sourceStream, createOptions, BitmapCacheOption.None);

            // Check source has valid frames
            if (sourceDecoder.Frames[0] != null && sourceDecoder.Frames[0].Metadata != null)
            {
                BitmapMetadata sourceMetadata = sourceDecoder.Frames[0].Metadata as BitmapMetadata;

                // Check there is a RegionInfo
                if (sourceMetadata.ContainsQuery(microsoftRegions))
                {
                    BitmapMetadata regionsMetadata = sourceMetadata.GetQuery(microsoftRegions) as BitmapMetadata;

                    // Loop through each Region
                    foreach (string regionQuery in regionsMetadata)
                    {
                        string regionFullQuery = microsoftRegions + regionQuery;

                        // Query for all the data for this region
                        BitmapMetadata regionMetadata = sourceMetadata.GetQuery(regionFullQuery) as BitmapMetadata;

                        if (regionMetadata != null)
                        {
                            if (regionMetadata.ContainsQuery(microsoftPersonDisplayName) &&
                                regionMetadata.ContainsQuery(microsoftRectangle))
                            {
                                Console.Writeline( regionMetadata.GetQuery(microsoftRectangle).ToString()));
                                 Console.WriteLine(regionMetadata.GetQuery(microsoftPersonDisplayName).ToString()));
                            }

                        }
                    }
                }
            }
        }
    }

Jamesjamesian

Have you come across a similar solution in Python? – Dullard

Nope. The code relies pretty heavily on Microsoft structures, and I'm not aware of any Python library with the equivalents. – Jamesjamesian

Answer 2

When possible, Windows Live Photo Gallery uses XMP to write metadata to picture files. See Metadata and the Windows Vista Photo Gallery for details.

Myungmyxedema

At what byte offset does the XMP start? – Jamesjamesian

In the Wikipedia article I linked above, it lists "Location in file types." For example, a JPEG has XMP data in "Application segment 1 (0xFFE1) with segment header 'ns.adobe.com/xap/1.0\x00'". – Myungmyxedema