A System.Drawing.Image object supports the addition of arbitrary metadata through the System.Drawing.Image.SetPropertyItem() and System.Drawing.Image.RemovePropertyItem() methods. This class encapsulates that property.

You can specify an integer Id for the property, along with its length (Len) in bytes and its type (a short). The value itself is an array of bytes, the length of which is determined by the Len property mentioned earlier.

As with much of the more advanced parts of the GDI+ framework, this byte-oriented arbitrary data storage hints rather heavily at the fact that it is a thin wrapper over an unmanaged (but undocumented) API.

public sealed class PropertyItem {
// Public Instance Properties
   public int Id{set; get; }
   public int Len{set; get; }
   public short Type{set; get; }
   public byte[ ] Value{set; get; }
}

Returned By

System.Drawing.Image.{GetPropertyItem(), PropertyItems}

Passed To

System.Drawing.Image.SetPropertyItem()