cross-posted from: https://programming.dev/post/37278389
Optical blur is an inherent property of any lens system and is challenging to model in modern cameras because of their complex optical elements. To tackle this challenge, we introduce a high‑dimensional neural representation of blur—the lens blur field—and a practical method for acquisition.
The lens blur field is a multilayer perceptron (MLP) designed to (1) accurately capture variations of the lens 2‑D point spread function over image‑plane location, focus setting, and optionally depth; and (2) represent these variations parametrically as a single, sensor‑specific function. The representation models the combined effects of defocus, diffraction, aberration, and accounts for sensor features such as pixel color filters and pixel‑specific micro‑lenses.
We provide a first‑of‑its‑kind dataset of 5‑D blur fields—for smartphone cameras, camera bodies equipped with a variety of lenses, etc. Finally, we show that acquired 5‑D blur fields are expressive and accurate enough to reveal, for the first time, differences in optical behavior of smartphone devices of the same make and model.
Just my guess. I could be wrong:
As the lens blur is mathematically fairly simple and spread across the whole image it’s likely already consistently replicated by AI in a similar way to real photos.
It’s easier for generative AI to spot, “understand”, and replicate a mathematical pattern than the number of fingers on a hand or limbs on a body.
It also helps that the current generation of image generation models essentially work by “deblurring” some random noise. Having a blur in the resulting image just means the model has to do less work in a sense.
Also a guess, isn’t a hand or any biological form not also the result of a mathematical pattern?
I do see how ai could replicate “a” blur but what it might not be able to do (yet) is replicate the unique blur of a specific device.
So maybe you couldn’t proof something is AI, but the physical lens as proof that it is not.
You wouldn’t share your physical lens for high-risk work (i.e. where you are anonymous) and since there’s no way to know whether a specific “blur” was produced by a physical lens or by AI, this won’t help in proving if something is AI.
Hands appear differently in different positions all over the frame in the photo so I maintain the hand pattern is less consistent and harder than lens blur.
But you’re right as the blur is a fingerprint you can match it to a lens and prove a photo is real that way.
It could be a useful tactic as much of AI detection is a way to find and prove AI fake so far.