>>711375,11This first part of your hypothesis
>1.Fake image numbersMeans nothing. You don't understand how file uploads are named on *chan sites.
When a file is uploaded, it is automatically given a UNIX timestamp number (
https://en.wikipedia.org/wiki/Unix_time ) which counts to the milliseconds and it is saved and it is to be displayed with that number as a name. This link you give
http://images.4chan.org/s4s/src/1375058634948.jpg simply means that a .jpg was uploaded to /s4s/ exactly on 1375058634948, ie Mon, 29 Jul 2013 00:43:54 GMT; while
http://images.4chan.org/s4s/src/1375058634949.jpg means there was never a .jpg uploaded on 1375058634949 to /s4s/.
And I don't know about others, but
http://images.4chan.org/s4s/src/1375058634949.jpg leads me to the 4chan-leech image, not a 404 error page. On the other hand, the constructing a link to those images showed in this supposed screencap lead me all to a 404.
In other words, your conclusion
>So the display of the leech image actually confirms that there was an image associated with the filename at one point in time.is wrong. It goes the either way, linking to and trying to download a previously uploaded file on 4chan can lead to either a 404 page or the 4chan-leech image; also, the latter happens when:
>If a black and white "4chan.org" image is being displayed instead of thumbnails, your browser/firewall/proxy is blocking the transmission of HTTP referers, which is triggering our anti-leech filter. Disable anything that might be blocking your browser's referer from being sent to our servers, and refresh the page.(
https://www.4chan.org/faq#noref )
TL;DR: There isn't one thing to be deduced purely from the screencap that confirms either case.
>>711375,13Which could just mean that any and all supposed images in this new screencap of /j/ (including
http://images.4chan.org/j/src/1369026900686.png ) were deleted for whatever reason, while the other image (
http://images.4chan.org/j/src/1252682694170.jpg ) has stayed in the server for a long time for whatever reason.
In any case not much can be said from this whole deal of a presumed /j/ screencap.