VB.net code to read image blob and expose as base 64 string from WebAPI

Let us first write a utility service as under

Imports Microsoft.Azure
Imports Microsoft.WindowsAzure.Storage
Imports Microsoft.WindowsAzure.Storage.Blob
Imports System.IO

Namespace WebApplication1.Utilities
	Public Class BlobStorageService

		Public Function ReadImageContent(blobName As String) As String
			Dim connectionString As String = CloudConfigurationManager.GetSetting("StorageConnectionString")

			' Retrieve storage account from connection string.
			Dim storageAccount As CloudStorageAccount = CloudStorageAccount.Parse(connectionString)

			' Create the blob client.
			Dim blobClient As CloudBlobClient = storageAccount.CreateCloudBlobClient()

			' Retrieve reference to a previously created container.
			Dim container As CloudBlobContainer = blobClient.GetContainerReference("testblobaccountimportcontainer")

			' Retrieve reference to a blob
			Dim blockBlob2 As CloudBlockBlob = container.GetBlockBlobReference(blobName)

			Dim datauri As String
			Using memoryStream = New MemoryStream()
				blockBlob2.DownloadToStream(memoryStream)
				Dim bytes = memoryStream.ToArray()
				Dim b64String = Convert.ToBase64String(bytes)
				datauri = "data:image/png;base64," + b64String
			End Using
			Return datauri
		End Function
	End Class
End Namespace

Then write the below in a controller

Imports System.Collections.Generic
Imports System.Linq
Imports System.Net
Imports System.Net.Http
Imports System.Web.Http
Imports WebApplication1.Utilities

Namespace WebApplication1.Controllers
	<RoutePrefix("BlobImage")> _
	Public Class ValuesController
		Inherits ApiController

		<Route("BlobImageData")> _
		<HttpGet> _
		Public Function GetPhotoData() As String
			Dim df As New BlobStorageService()
			Dim blobImageContent = df.ReadImageContent("Capture.PNG")
			Return blobImageContent
		End Function
	End Class
End Namespace