DetectFacesSample.cs

const float CONFIDENCE_LEVEL = 90;
var count = 0;

using(var source = new MemoryStream(image))
{
    var request = new DetectFacesRequest { Image = new Image() { Bytes = source }, Attributes = new List<string> { "ALL" } };

    var response = await amazonRekognitionClient.DetectFacesAsync(request);

    foreach(var faceDetail in response.FaceDetails)
    {
        Console.WriteLine($"Person {++count}");

        Console.WriteLine(faceDetail.Gender.Confidence > CONFIDENCE_LEVEL
                          && faceDetail.Gender.Value.Value.Equals("male", StringComparison.InvariantCultureIgnoreCase)
                ? "appears to be male"
                : "appears to be female");

        Console.WriteLine(faceDetail.Smile.Confidence > CONFIDENCE_LEVEL && faceDetail.Smile.Value is true ? "smiling" : "not smiling");
        Console.WriteLine(faceDetail.Beard.Confidence > CONFIDENCE_LEVEL && faceDetail.Beard.Value is true ? "has a beard" : "does not have a beard");

        Console.WriteLine();
    }
}