Reading data metadata from JPEG, XMP or EXIF in C#

Question

I've been looking around for a decent way of reading metadata (specifically, the date taken) from JPEG files in C#, and am coming up a little short. Existing information, as far as I can see, shows code like the following;

BitmapMetadata bmd = (BitmapMetadata)frame.Metadata;
string a1 = (string)bmd.GetQuery("/app1/ifd/exif:{uint=36867}");

But in my ignorance I have no idea what bit of metadata GetQuery() will return, or what to pass it.

I want to attempt reading XMP first, falling back to EXIF if XMP does not exist. Is there a simple way of doing this?

Thanks.

Answer 1

The following seems to work nicely, but if there's something bad about it, I'd appreciate any comments.

    public string GetDate(FileInfo f)
    {
        using(FileStream fs = new FileStream(f.FullName, FileMode.Open, FileAccess.Read, FileShare.Read))
        {
            BitmapSource img = BitmapFrame.Create(fs);
            BitmapMetadata md = (BitmapMetadata)img.Metadata;
            string date = md.DateTaken;
            Console.WriteLine(date);
            return date;
        }
    }

Answer 2

I've ported my long-time open-source Java library to .NET recently, and it supports XMP, Exif, ICC, JFIF and many more types of metadata across a range of image formats. It will definitely achieve what you're after.

https://github.com/drewnoakes/metadata-extractor-dotnet

var directories = ImageMetadataReader.ReadMetadata(imagePath);
var subIfdDirectory = directories.OfType<ExifSubIfdDirectory>().FirstOrDefault();
var dateTime = subIfdDirectory?.GetDescription(ExifDirectoryBase.TagDateTime);

This library also supports XMP data, via a C# port of Adobe's XmpCore library for Java.

https://github.com/drewnoakes/xmp-core-dotnet

Answer 3

If you're struggling with XMP jn jpeg, this works. It's not called brutal for nothing!

public class BrutalXmp
{
    public XmlDocument ExtractXmp(byte[] jpegBytes)
    {
        var asString = Encoding.UTF8.GetString(jpegBytes);
        var start = asString.IndexOf("<x:xmpmeta");
        var end = asString.IndexOf("</x:xmpmeta>") + 12;
        if (start == -1 || end == -1)
            return null;
        var justTheMeta = asString.Substring(start, end - start);
        var returnVal = new XmlDocument();
        returnVal.LoadXml(justTheMeta);
        return returnVal;
    }
}

Answer 4

我认为您正在做的是一个很好的解决方案，因为 System.DateTaken 处理程序会自动应用回退到其他命名空间的Photo 元数据策略来查找值是否存在。

Answer 5

If you are trying to access these properties:

You can do the following:

1. Add a reference to C:\Windows\System32\Shell32.dll. VS 2022 automatically creates an interop to interact with the ActiveX library.
2. I added the following code to a button click event to demonstrate getting the data desired.

Code Sample:

Shell32.Shell shell = new Shell32.Shell();
Shell32.Shell objShell = shell.Application;
Shell32.Folder folder = objShell.NameSpace(@"D:\TestFolder");
Shell32.FolderItem folderItem = folder.ParseName("TestMetadata.jpg");
for (int tagIndex = 0; tagIndex < 321; tagIndex++)
{
   // Pass null in the first parameter to get the tagName
   string tagName = folder.GetDetailsOf(null, tagIndex);

   if (!string.IsNullOrEmpty(tagName))
   {
      // Pass an instance of Shell32.FolderItem to get the tsg value.
      string tagValue = folder.GetDetailsOf(folderItem, tagIndex);

      Console.WriteLine($"[{tagIndex}] {tagName} = {tagValue}");
   }
}

The console will display strings representing the values of interest. I'm not sure why, by dates containing single digit month and/or day values will display a? for the 0 digit. These can easily be replaced and then the date can be parsed. Here is the output for some of the interesting ones displayed in the Properties\Details tab:

[3] Date modified = 9/3/2022 2:37 PM
[4] Date created = 9/3/2022 2:35 PM
[5] Date accessed = 9/3/2022 10:38 PM
[12] Date taken = ?1/?1/?2022 ??2:36 PM
[18] Tags = Metadata Tags
[21] Title = My Test Title
[22] Subject = Being and Nothingness
[24] Comments = Kilroy wuz here!
[25] Copyright = 2022
[136] Date acquired = ?1/?2/?2022 ??2:36 PM

As far as I am aware, there are as many as 320 different tag types.

Answer 6

My company makes a .NET toolkit that includes XMP and EXIF parsers.

The typical process is something like this:

XmpParser parser = new XmpParser();
System.Xml.XmlDocument xml = (System.Xml.XmlDocument)parser.ParseFromImage(stream, frameIndex);

for EXIF you would do this:

ExitParser parser = new ExifParser();
ExifCollection exif = parser.ParseFromImage(stream, frameIndex);

obviously, frameIndex would be 0 for JPEG.