If everybody does that with everything, blockchains get infeasibly large. If not, anybody can go and register things on a blockchain that the original creator didn't and then claim they were first.
You would just use any sort of aggregation scheme to include multiple hashes at once. Even concatenating 1000 image hashes and hashing that would allow you to prove later that they were all included.
That just moves the problem from where to store the blockchain to where to store the concatenated hashes.
If this is some cloud provider, what are you getting from a blockchain? Just have the cloud provider do the certification. If they betray you or go out of business you've lost your hashes anyway.
If it's stored on the endpoint device, you can't prove it anymore if the device gets lost or damaged. In theory people could back them up, but we all know perfectly well that ordinary people are not going to do that unless it's automated.
So then you're back to storing them in a distributed system, i.e. making them a necessary part of the blockchain. And then it gets too big.
On blockchain, you store the aggregated signature / Merkle root of all the images hashes.
For the actual hashes, you can back them up in multiple places literally anywhere, including the image metadata itself. The advantage is nobody needs to trust a cloud provider to keep that S3 object intact and online in perpetuity, or the owner to keep paying for that, because the original date is on a public blockchain synced by 10,000s of nodes.