Getting Started (dotnet)

metadata-extractor is available via NuGet, or via a download from the releases page.

Using this library is straightforward. Conceptually there are two steps to its usage:

1. Read Directory objects from an image
2. Query the Directory objects to retrieve one or more values

NOTE:

• These examples are based upon version 2 of the API. Earlier versions may differ slightly.
• using directives and exception handling code have been omitted for clarity.
• Fully-featured sample classes are available in the source distribution.

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1. Read Metadata

The simplest way to read metadata is to use ImageMetadataReader.

If you know the type of file you're reading from then you can replace ImageMetadataReader with a more specific reader, such as JpegMetadataReader. Using ImageMetadataReader is often safer as it uses FileTypeDetector to inspect the file's contents in order to determine which decoding method to use and incurs very little overhead.

From a File

For an image file of any supported type, use:

var directories = ImageMetadataReader.ReadMetadata("myImage.jpg");

From a stream

Reading from a Stream is much the same:

var directories = ImageMetadataReader.ReadMetadata(stream);

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2. Query Tags

After reading metadata, you'll have zero or more Directory objects. These in turn contain zero or more Tag objects. Tags hold values representing the metadata of the source image.

Print out all Tag values

foreach (var directory in directories)
{
    foreach (var tag in directory.Tags)
    {
        Console.WriteLine(tag);
    }
}

Query the raw value of a specific Tag

// obtain the Exif SubIFD directory
var directory = directories.OfType<ExifSubIfdDirectory>().FirstOrDefault();

if (directory != null)
{
    // query the tag's value
    if (directory.TryGetDateTime(ExifDirectoryBase.TagDateTimeOriginal, out var dateTime))
        return dateTime;
}

Note that tag values have specific data types. Attempts will be made to convert to the type you request, but this is not always possible.

Query a decoded description of a specific Tag

If you only wish to display a friendly string version of the tag's value, simply call Tag.ToString(). Alternatively, you can wrap the directory with a Descriptor and have strongly-typed access with descriptive method names:

// obtain a specific directory
var directory = directories.OfType<ExifSubIfdDirectory>().FirstOrDefault();

if (directory != null)
{
    // create a descriptor
    var descriptor = new ExifSubIfdDescriptor(directory);
    
    // get tag description
    String program = descriptor.GetExposureProgramDescription();
}

In the above example, program would contain a detailed string such as "Manual control" or "Aperture Priority", whereas the raw tag value is actually an integer. Descriptors not only decode enum values, but also prepend/append units ("-1 EV", "f/2.8") and provide methods that calculate derived properties for convenience.