README.md

Image Caption Bot Sample

A sample bot that illustrates how to use the Microsoft Cognitive Services Computer Vision API to analyze an image from a stream or a URL and return to the user the image caption.

Prerequisites

The minimum prerequisites to run this sample are:

• The latest update of Visual Studio 2015. You can download the community version here for free.
• The Bot Framework Emulator. To install the Bot Framework Emulator, download it from here. Please refer to this documentation article to know more about the Bot Framework Emulator.
• This sample currently uses a free trial Microsoft Cognitive service key with limited QPS. Please subscribe to Vision API services here and update the MicrosoftVisionApiKey key in Web.config file to try it out further.

Code Highlights

Microsoft Computer Vision API provides a number of methods that allows you to analyze an image. Check out IVisionServiceClient.cs for a complete reference of the methods available. In this sample we are using AnalyzeImageAsync(string url, ...) and AnalyzeImageAsync(Stream imageStream, ...) to analyze an image from a URL and stream respectively. The AnalyzeImageAsync method returns AnalysisResult.cs class which contains rich information about the image:

namespace Microsoft.ProjectOxford.Vision.Contract
{
    public class AnalysisResult
    {
        public AnalysisResult();

        public Adult Adult { get; set; }
        public Category[] Categories { get; set; }
        public Color Color { get; set; }
        public Description Description { get; set; }
        public Face[] Faces { get; set; }
        public ImageType ImageType { get; set; }
        public Metadata Metadata { get; set; }
        public Guid RequestId { get; set; }
        public Tag[] Tags { get; set; }
    }
}

In this sample we are using the API to get the image description and send it back to the user. Check out the use of the MicrosoftCognitiveCaptionService.GetCaptionAsync() method in the MicrosoftCognitiveCaptionService.cs class.

/// <summary>
/// Gets the caption of the image from an image stream.
/// <remarks>
/// This method calls <see cref="IVisionServiceClient.AnalyzeImageAsync(Stream, string[])"/> and
/// returns the first caption from the returned <see cref="AnalysisResult.Description"/>
/// </remarks>
/// </summary>
/// <param name="stream">The stream to an image.</param>
/// <returns>Description if caption found, null otherwise.</returns>
public async Task<string> GetCaptionAsync(Stream stream)
{
    var client = new VisionServiceClient(ApiKey);
    var result = await client.AnalyzeImageAsync(stream, VisualFeatures);
    return ProcessAnalysisResult(result);
}

/// <summary>
/// Processes the analysis result.
/// </summary>
/// <param name="result">The result.</param>
/// <returns>The caption if found, error message otherwise.</returns>
private static string ProcessAnalysisResult(AnalysisResult result)
{
    string message = result?.Description?.Captions.FirstOrDefault()?.Text;

    return string.IsNullOrEmpty(message) ?
                "Couldn't find a caption for this one" :
                "I think it's " + message;
}

Outcome

You will see the following when connecting the Bot to the Emulator and send it an image URL:

Input:

Output:

You can also choose to upload an image directly to the bot:

More Information

To get more information about how to get started in Bot Builder for .NET and Microsoft Cognitive Services Computer Vision API please review the following resources:

• Bot Builder for .NET
• Microsoft Cognitive Services Computer Vision API
• Microsoft Cognitive Services Computer Vision API Windows Client Library