Brian Gregory wrote:
On 11/08/2018 17:50, nospam wrote:
In article , Mr. Man-wai
Chang wrote:


But how do you get a 100% TRUE lossless original? Using good, old
film-based cameras?

film is more lossy than digital.


I bet there are many film cameras that are way way better than my first
ever webcam - 320x240 resolution fixed focus. Looked horrible in
anything except bright sunlight. Luckily is was cheap so I wasn't that
bothered. Nevertheless IT WAS DIGITAL.


If you have a static scene, and you run the webcam in
"picture" mode instead of "video" mode, you can actually
take two pictures with a bad webcam, and average them
in Photoshop as (A+B)/2 and the sensor noise will be
attenuated.

I did some pictures for a user manual that way. Shot
about 70 images, and averaged them to improve the
quality. It was before I got a digital camera.

In testing, averaging an excessive number of images
doesn't help. I tried for example, averaging
16 images in NIHimage, and it really doesn't help
all that much. But if you place your camera on a
tripod, and the scene is static, and you shoot
the two pictures one after the other, then
averaging the two pictures reduces the sensor noise.
The biggest improvement comes by using two images.

It still isn't digital camera quality, but at
least it's a small improvement.

Sony HAD sensors are better than your average
webcam. And you're not likely to get one for $10 :-)
Sony has no interest in supplying the $10 webcam
market.

https://en.wikipedia.org/wiki/HAD_CCD
https://en.wikipedia.org/wiki/Hole_accumulation_diode

That's what you'd like to see in a webcam.

Paul