I think it took about 40 hours of non-stop work to manage the event and other bbcode related details.

This will create chaos and I will simply have to do more work. No matter the size of the image (even if they are all the same) some users will not fulfill the conditions and some users will send "distant/enlarged/upside" down photos etc.

When I create a bbcdoe table I simply re-upload the "best" of the submitted photos with the focus on the pizza without the background or other distracting aspects. This way we get a grid of participants. If any photo is slightly distorted, it is not a problem against the background of the huge amount of work done.