Comprehensive Detailed Explanation

You’re adding multiple images for each person into a PersonGroup using the Face API SDK.

File.OpenRead(imagePath) returns a Stream, so the using declaration must declare Stream t = File.OpenRead(imagePath) .

To upload an image from a stream to a person in a person group, call

faceClient.PersonGroupPerson.AddFaceFromStreamAsync(personGroupId, personId, t);

Putting it together:

Parallel.For( 0 , PersonCount, async i = >

{

Guid personId = persons[i].PersonId;

string personImageDir = $ " /path/to/person/ {i} /images " ;

foreach ( string imagePath in Directory.GetFiles(personImageDir, " *.jpg " ))

{

using (Stream t = File.OpenRead(imagePath))

{

await faceClient.PersonGroupPerson.AddFaceFromStreamAsync(

personGroupId, personId, t);

}

}

});

This loops the images for each person, opens each as a stream, and adds the face to the specified person in the person group.

References

Microsoft Docs – Face API: Add a face to a person ( AddFaceFromStreamAsync , AddFaceFromUrlAsync ) in PersonGroupPerson operations.

https://learn.microsoft.com/azure/ai-services/face/ (see SDK/PersonGroupPerson methods)

NET File.OpenRead returns Stream .

https://learn.microsoft.com/dotnet/api/system.io.file.openread