Image swap

Image swap in the same thread. In the thread order, the first post has its image overwritten by the second's.

Image swap refers to the rare event when a post's attached image is erroneously replaced by the attached image of an unrelated post. Sometimes only the thumbnail is swapped, other times a "full swap" swaps the true, expanded images entirely. Sometimes there is no swap, one simply overwrites the other. Image swaps seem to happen when images are processed at the same time in the eyes of 4chan's servers.

4chan servers index images by a 13-digit UNIX timestamp which has the precision of a millisecond, which makes collisions not too hard given you roll the dice enough times. As of 2021, image swaps are not too infrequent on boards like /pol/, /v/ and /vg/, which average ~100 posts per minute.

Theoretically, an image swap can happen not just with two images but three, four, five... Although I couldn't find any instances of more than two (but I didn't search either). Of course the already minuscule chance of two images getting processed at the exact millisecond exponentially diminishes with each increment. But it shouldn't be impossible.

Image swap across two /mlp/ and /tv/ posts, to the amusement of /tv/ posters. 2013. It's unknown if crossboard image swaps are still possible in 2021. Server changes now probably separate the file path to images by board, so at least, images are no longer conflated like this.

Further reading

- Instances of image swaps are often reported at the time's respective meta discussion general (if it is alive): [1]