Ok, so the wallet takes a picture and the data is stored in the blockchain, yes? Does the user need to spend a coin or an amount to create the TX that the data is stored in and assuming that the black data area that the other chains use is where the image data goes, how is it protected? Also, I could be totally wrong, but the last I remember there was about 80 bytes of blank space in a Bitcoin TX. That is not room for a image of any size, but really for a symbolic or database link of some kind and that might involve a centralized point of contact.
The application tags each photo with an address linked to the users wallet, so each photo has a corresponding address which is only held by one user. These addresses are what dictate who owns what photo in our photo storage and our weekly rankings. This bypasses any issues of byte size or trying to store images in other formats like hexadecimal. There would be a point of contact, being our servers tagged images which informs us who owns what, but seeing this isn't dealing with the monetary side of things the risk is negligible. It provides us and the user a layer of authentication which allows us to moderate photo rankings and ensure proper ownership when photos are lost.
The first blockchain layer of Snapshot has no monetary capacity, it is merely to serve as record ledger, so transactions do happen but users do not pay for them. The only costs that are incurred by users in Snapshot is when they opt for photo retrieval or purchase stickers, UI skins etc, and that is done with ERC20 Snap tokens, not the blockchain for ledger purposes.
Issues like the above are why we opted for a two blockchain technology, we had to decouple the means of payment from the means of record keeping.
Thank you for asking thought provoking questions, these are the types of things that not only clarify what Snapshot is to you, but to everyone else who might have been wondering the same thing.