A lossy compressor isn't just like a lossless compressor. Especially not one that has ~2 bytes for each input image.

I agree with you. My intuition is also that SD itself is not a violation of copyright.

That said it can sometimes be in violation of copyright if it creates a specific image that is “too close to another original” (just like a human would be in violation even if they never previously saw that image).

But the above is just my intuition (and possibly yours) that doesn’t mean a lawyer couldn’t make the argument that it’s a ”good enough lossy compression - just like jpeg but smaller” and therefore “contains the images in just 2 bytes”.

That lawyer may fail to win the argument, but there is a chance that they do win the argument! Especially as researchers keep making Diffusion and SD models better and better at being compression algos (which is a topic people are actively working on).

How many bytes make it an original work vs a compressed copy?

Usually judges would care more about whether the bytes came from than how many of them there are.

Since SD is trained by gradient updating against several different images at the same time, it of course never copies any image bits straight into it. Since it's a latent-diffusion model, any actual "image"ness is limited to the VAE, so any fractional bits would be in there.

The text encoder (LAION OpenCLIP) does have bits from elsewhere copied straight into it to build the tokens list.

https://huggingface.co/stabilityai/stable-diffusion-2-1/raw/...

The important distinction then is using another program or device to analyze the bits but without copying them, that takes its own new impression? Like using a camera?

Well, theoretically more like a vague memory of it or taking notes on it.

“any fractional bits would be in there if you want to look.”

What do you mean by this in the context of generating images via prompt? “Fractional bits” don’t make sense and it’s more misleading if anything. Regardless, a model violating criteria for being within fair use will always be judged by the outputs it generates rather than its composing bytes (which can be independent)

Fractional bits makes perfect sense. Do you know how arithmetic coders work?

One, of your compressor is specialised enough…so you can see how slippery this argument can be.

So it's fine to distribute copyrighted works, as long as they're jpeg(lossy) encoded? I don't think the law would agree with you.

If I compress a copyrighted work down to two bytes and publish that, I think that judges would declare it legal. If it can't be uncompressed to resemble the copyrighted work in any sense, no judge is going to declare it illegal.