'save the selected size:
File.WriteMap(File.DirInternal, "size.txt", CreateMap("width": size.Width, "height": size.Height)
'load it when you want to set the picture size:
If File.Exists(File.DirInternal, "size.txt") THen
Dim m As Map = File.ReadMap(File.DirInternal, "size.txt")
CamEx.SetPictureSize(m.Get("width"), m.Get("height"))
End If