When selecting the deployment environment as Amazon AWS, it comes up with a nice tool called Amazon S3 (Amazon Simple Storage Service) which can be used as a storage for static content, especially as a content delivery network (CDN).
Amazon S3 provides a simple web services interface that can be used to store and retrieve any amount of data, at any time, from anywhere on the web, and it also consists with a set of APIs to manipulate it via most of the popular programming laguages.
In our project we maintained a separate server, accessed via FTP to store all the images used in the application. The application was developed on top of CI framework, so we didn’t had any problem communicating with the FTP server since the framework itself was geared with a feature rich FTP library. Amazon AWS environment was selected as the hosting environment. With the introduction of Amazon AWS environment we opted to use Amazon S3 as our image repositiry for the project. I found an Amazon S3 PHP library developed for CI on Git Hub. Later extended it to suite our requirements. It can be downloaded over here.