imgddcore: can we parameterize phash hash_size?

[tgpfeiffer]

In https://github.com/JohannesBuchner/imagehash/blob/4e289ebe056b961aa19fb1b50f5bdc66c87e0d55/imagehash/__init__.py the hash_size parameter can be changed to increase accuracy. In this repository the hash size is hardcoded to 8

imgdd/crates/imgddcore/src/hashing.rs

Line 137 in 3dcfca5

const HASH_SIZE: usize = 8;

and because all hashes share the same underlying ImageHash data structure using u64

imgdd/crates/imgddcore/src/hashing.rs

Lines 12 to 14 in 3dcfca5

	pub struct ImageHash {
	hash: u64,
	}

it's not obvious how to make the code more flexible.

I'm happy to work on this, but do you have any suggestion/preference on how it should be done? @aastopher

[aastopher]

@tgpfeiffer

This is a current limitation of the existing design pattern. I hard coded the hash size as increasing this does increase accuracy, however it has negative performance implications at certain sizes, so I omitted this feature for the early versions of this library since it also implied a more complex ImageHash pattern where the correct type is assigned as the underlying structure given different hash sizes.

Feel free to make suggestions on the approach or throw a pr together on what you're going for.