Whether you can turn on uploading images that are only visible to private people?

Whether you can turn on uploading images that are only visible to private people?

No such feature that I know of (besides hidden state which is for yourself only). Though if you post images without associating to any model, don't tag reasonably and use an unknown account, should make it quite inaccessible to anyone but crawlers since there's a constant torrent of uploads which drown out the "newest" sort, and there's no other means of reference besides the account. Nonetheless, there are certainly more secure methods of transfer and image uploading elsewhere.