“Yes, there were so many people resurrected from the dead back then, how would you ever know which one it was?”
The image itself, and the unknown manner of how it was produced also does not confirm (prove) that the person in the image was “resurrected”. It can only confirm that the shroud was placed around whoever it is in the image. When, how, why and with whom cannot be determined by any facts that can be deciphered from the shroud alone.
Regardless, belief or non-belief in such things cannot be a determining factor in a Christian’s faith. It is enough that G-d knows more than we do, always, and we can leave understanding and confirmation of such things up to G-d. We can trust that G-d will answer such questions to ALL of us when and if it is important for us to have the answers. And by G-d, I do not mean some human activity claiming to be the work of G-d.