you can create a new entity which inherits from system.FileDocument and associate it with your current entity then you will be able to use the image uploader
also refer to the documentation see example here
What you will need to do is create an Entity B that inherits from System.FileDocument. Then create a reference from A to B for each attribute that you want a file to be uploaded for. Or if you do not mind that all files are mixed up you can create 1 reference Set.
The first seems the better option in your case because you have a specific file for each attribute. However the latter will allow you to easily add additional attributes.