In case your point is not obvious to someone, 10000! is FAR larger than 100!*100! (by something like 350,000 orders of magnitude), so the possibility space is v

In case your point is not obvious to someone, 10000! is FAR larger than 100!*100! (by something like 350,000 orders of magnitude), so the possibility space is vastly bigger if you shuffle the pixels individually than if you shuffle columns first, then rows.