The images stored on file system can disappear when your application stops, crashes, or moves. It should not be used for content that you want to persist. Further, the file system storage is not scalable. That is to say if more than one instance of your app is running the local storage is only visible to a specific instance of the app, and is not visible or shared across all instances.
To meet your requirements, a local service such as MongoDB GridFS, MySQL with blob data type or external blob stores such as Box.net or Amazon S3 can be used.