How to prepare WSP for delta deployment?


I have some images to be deployed in the delta deployment. In the initial deployment i deployed 10 images.
In delta deployment 4 are updated which i need to deploy on production server.
My WSP project is in TFS, which is maintaning all the Images. I don't want to remove 6 images which are not updated from WSP project RootFiles folder.
But at same time I want only 4 changed images to go in the WSP package.