public async Task<AnalysisResult> GetImageDescription(Stream imageStream)  
{  
   VisionServiceClient visionClient = new VisionServiceClient("a338648c0df347c6b3b9e46ea2022fcd", "https://westcentralus.api.cognitive.microsoft.com/vision/v2.0");  
   VisualFeature[] features = { VisualFeature.Tags, VisualFeature.Categories, VisualFeature.Description };  
   return await visionClient.AnalyzeImageAsync(imageStream, features.ToList(), null);  
}