Domain types for image metadata, including timestamps, orientation, GPS/location data, processing state, people, faces, and tags. Models use return-new-instance change helpers rather than in-place mutation and support Newtonsoft.Json serialization.

dotnet add package TCSystem.MetaData

• Image holds file details, dates, orientation, location, processing flags, text tags, and person tags. Its change methods return updated copies instead of modifying the supplied instance.
• PersonTag links a Person to a detected Face, including its rectangle, detector, visibility, quality, and optional 128-value descriptor.
• Location, Address, and GpsPoint model geographic metadata; GPS points can calculate Haversine distance.
• Fixed-point coordinates, normalized Rectangle values, and Orientation provide stable face geometry and EXIF transformations.
• Core models provide Newtonsoft.Json serialization helpers.
• ProcessingInfos tracks which analysis calculations have already been run for an image, such as face-detection and image-classification passes.

FaceQuality only classifies suitability for finding similar faces; it does not control matching. The semantic scale is Unusable → Poor → Normal → Good → Excellent.

Persisted values are Normal = 0, Poor = 1, Good = 2, Unusable = 3, and Excellent = 4. They preserve existing JSON and SQLite compatibility but are not in semantic order, so compare named values rather than integers.

Repository-wide prerequisites, target frameworks, dependencies, build, test, coverage, and API-documentation instructions are maintained in the main README.