Though I didn't have practical experience in doing this, I believe this can be achieved by writing a custom activity which in turn calls 'UploadImageFile' OOTB activity against all your images(Binary Files of type Rule-File-Binary) that you want to upload.
Go to Operator ID rule (open your own), use UI Inspector to see what control is used to upload images. Read a help article about working with images. Pega has a number of activities which work with a server file system, e.g. search uploadFile or downloadFile.