Re: Screenshots etc.

J. P. Gilliver wrote:
> "Just because you're paranoid, doesn't mean they _aren't_ out to get
> you" - but!

:)

I was trained in TLA-level privacy, so to speak, where I was told you don't
protect against what you think they'll do, but what you know they can do.

Privacy is a million things, most of which are easy to do, where protecting
camera images from fingerprinting is something that's relatively easy.

Of course, as you noted, screenshots are different from camera images.
In theory, GPU drivers or font renderers could introduce artifacts, but
operating systems treat a screenshot as a direct copy of the framebuffer,
(not as a photograph of the screen). That design choice eliminates most of
the natural device-specific quirks that camera forensics relies on.

For example, this is a screenshot of an image posted to this ng long ago.
 <https://i.postimg.cc/Gh22Sb2N/desktop.jpg>


> I think the vast majority of screenshots uploaded are actually screen
> _captures_, which obviously do not have the pixel-stains of a camera
> shot. On the whole, the only time a camera is used is in discussion of
> BIOS and similar screens (or, occasionally, where things happen too fast
> - though you then probably need a video camera in order to be able to
> get the image you want; even then, screen capture can be video).
> 
> So, yes, your privacy concern _can_ be valid - but only for a small
> fraction of screen "shots".

I never disagree with a logically sensible statement so I agree with you
that for "screenshots" camera sensor imperfections don't show up in them.

For operating system newsgroups, as you noted, camera shots are rarely
posted, but sometimes we post our equipment configurations to the ng.
  <https://i.postimg.cc/6QJqK6Cj/desktop02.jpg>

Note though that privacy is a million things, of which most people only
know a half dozen, where a screenshot of a camera image confers privacy.

Only visible artifacts from the camera photo will carry over, such as:
a. Noise that is visibly present in the image
b. Lens distortion that is visibly present
c. Chromatic aberration that is visibly present
d. Compression artifacts
e. Blurring, vignetting, etc.

If the camera photo shows grain, color shifts, or distortion, the
screenshot will faithfully copy those pixels. but these are not the
forensic "sensor fingerprints" used to identify a specific device.

So one basic privacy step is to screenshot camera images before posting.
-- 
Often those who most deprecate privacy are those who least understand it.