Re: PSA Using Python Pillow to foil camera image PRNU fingerprinting

Piergiorgio Sartor
<[email protected]> wrote:
> On 01/08/2026 01.13, Maria Sophia wrote:
> [...]
> 
> I'm under the impression there is some
> confusion here.

To be expected considering who the OP is...

> On the other hand, PRNU will have some
> spatial statistical properties, even if
> it is fixed for a given sensor.
> 
> Now, assuming we have some PRNU from some
> unrelated sensor (meaning we can generate
> a spatial noise with same statistical
> properties), it would be possible to
> consider to apply this noise ("apply", not
> "add") to a given image.
> 
> This means the effective PRNU will be the
> combination ("combination", not "sum") of
> two PRNUs, resulting in a new fingerprint,
> different from the original one.
> 
> So, de-noising is not really needed, but it
> might be helpful to reduce / remove / modify
> the original PRNU, so that the applied one
> will be more evident.

The two main issues regarding PRNU that the OP has missed when jumping to
conclusions are: 1) it is probabilitic, 2) it is comparative. 

That means for 1)  there's no guarantee that the noise in your camera
sensor is unique to you. It might be common, or very similar, to all
cameras of that model and batch. The statistical model is based on small
samples of camera sensors so it isn't a globally accurate model. 

For 2) that means it cannot state which device was used to take a photo
without having the device in question in your possession. 

Just like ballistics. Once you have a suspect gun in your possession you
can make some assessment of the probability of whether that gun fired a
particular round.