The antonyms for "brought into the open" would be kept hidden or concealed. This could imply that something is being kept secret or withheld from public knowledge. It could also suggest that there is a lack of transparency or honesty involved in the situation. Alternatively, the opposite of "brought into the open" could be kept private, meaning that something is being intentionally kept between a select group of individuals and not shared with the public. Both scenarios have their own set of implications and consequences, depending on the context in which they are used.