Vision API C# - reading stored image's URL in Azure

Question

    //If the user uploaded an image, read it, and send it to the Vision API
if (activity.Attachments.Any() && activity.Attachments.First().ContentType.Contains("image"))
{
   //stores image url (parsed from attachment or mess`enter code here`age)
   string uploadedImageUrl = activity.Attachments.First().ContentUrl; ;
   uploadedImageUrl = HttpUtility.UrlDecode(uploadedImageUrl.Substring(uploadedImageUrl.IndexOf("file=") + 5));

   using (Stream imageFileStream = File.OpenRead(uploadedImageUrl))
   {
       try
       {
            analysisResult = await visionClient.AnalyzeImageAsync(imageFileStream, visualFeatures);
       }
       catch (Exception e)
       {
            analysisResult = null; //on error, reset analysis result to null
       }
   }
}
//Else, if the user did not upload an image, determine if the message contains a url, and send it to the Vision API
else
{
    try
    {
        analysisResult = await visionClient.AnalyzeImageAsync(activity.Text, visualFeatures);
    }
    catch (Exception e)
    {
        analysisResult = null; //on error, reset analysis result to null
    }
}  

I am trying the code above. I got the code from here: https://docs.botframework.com/en-us/bot-intelligence/vision/#example-vision-bot.

As is, the code does what it can do when ran locally, but reading the image's URL from an uploaded file doesn't work after I published my bot to Azure and ran it from there.

I attempted to debug by attaching Visual Studio directly to my published webapp bot in Azure. It looked like the webapp is unable read the stored image's URL from the Azure server temp storage location or can't access the temp storage location.

This line:

uploadedImageUrl = HttpUtility.UrlDecode(uploadedImageUrl.Substring(uploadedImageUrl.IndexOf("file=") + 5));

Shows this value: "https://bcattachmentsprod.blob.core.windows.net/at4984/Gv4cOx6OdSl- original"

Then, this line:

using (Stream imageFileStream = File.OpenRead(uploadedImageUrl))

Changes the value to: "s://bcattachmentsprod.blob.core.windows.net/at4984/Gv4cOx6OdSl-original"

And then it just stops.

Has anyone ran into an issue like this? How do I go about solving this issue?

Thanks!

Answer 1

If you have a image URL, you should simply call AnalyzeImageAsync with that URL instead of creating a stream as you have. The File class should be used for files on your local drive/network. By creating a stream, you download the image once to your VM, then upload it to the vision service, doubling the work.