Display image from byte array in ASP.NET MVC
Displaying images from wellknown URLs is quite straightforward. At times, however, you need to display images that are available as raw binary data. Consider, for example, that you are building a Captcha system that generates images on the fly. These images won't reside on the server as physical files. They will be generated and held in memory using System.Drawing classes (or something similar). To display them you can't point the src attribute of an <img> element to a particular URL as such.
http://www.binaryintellect.net/articles/e6d71127-1f12-4555-879b-6a859947eafa.aspx