When using Azure Blob Storage you should set the header Cache Control to prevent the clients from fetching the picture every time they come to your site. An easy way of doing this is by adding this code last in AzurePictureService.cs in SaveThumb:
blockBlob.FetchAttributes();
var cacheControl = "max-age=2592000, must-revalidate";
blockBlob.Properties.CacheControl = cacheControl;
blockBlob.SetProperties();
You could also add the following code to set the content type:
var fileExtension = Path.GetExtension(thumbFileName);
var contentType = "application/octet-stream";
switch (fileExtension)
{
case ".jpg": contentType = "image/jpeg"; break;
case ".jpeg": contentType = "image/jpeg"; break;
case ".png": contentType = "image/png"; break;
case ".gif": contentType = "image/gif"; break;
}
blockBlob.Properties.ContentType = contentType;