At the moment I have TalkImg configured for uploads of up to 3MB, but the forum only accepts up to 2.5MB.
The image is 1403233 bytes. Somehow the upload to you server doubles it. Can you check if it's exactly double the size? Something weird is happening during upload.Yes, this is another point that I will have to investigate, it was something that should not be happening.
It really doesn't make sense, sometimes the way the image was originally compressed can cause this type of problem. Either way, it was something that shouldn't happen. But I will investigate and see what I can do.