k1 pixel shift - can you see the different?

James O'Neill wrote:

JeremieB wrote:

Pixel shift of course may have an effect on details, but that depends a lot on overall sharpness of the scene (lens vs sensor etc).

But pixel shift has a definitive effect on reducing noise, as you take the mean of 4 captures instead of just 1.

I have never understood HOW this works. I've done tests to show that it DOES work.

If you have PS off, a pixel is might be Red, Green or Blue. The other colours are made up the average of the neighbours with that colour.

But you have PS on there is a single reading for Red and Blue and two for green each site. There should be less averaging with PS. (Unless each image is demozaiced and the 4 are averaged, but that would reduce resolution)

There's more light captured, so there should be less noise, but I can't get my head round the mechanism, unless it the extra data playing a role in NR.

Take 1 picture of size m x n, resize in half to get a picture of size m/2 x n/2 (remove high frequencies before resizing of course to avoid aliasing).

New picture will have better S/N ratio, it's sort of pixel binning in fact (half pixels with 4 times more "light" per pixel). That's the averaging I talk about. Averaging being a blur - there's less visible noise and better S/N. That's also exactly the same effect as when we capture a huge number of photos in astro, then stack them to reduce noise. Averaged same signal remains same signal, only the noise gets step by step lower / closer to the "true" signal (well, shot noise, noise that is not random is not concerned).

PS works the same except it starts from 4 images (that can be considered the same as 1 image of twice the size in each dimension, That's what others do with super resolution). Pentax PS prefers binning to produce an image with less noise, and with added value of cancelling the Bayer filter by moving the sensor appropriately. Of course you don't need PS just to lower noise with this technique, as I noticed about astro for example. But that + Bayer cancelling makes it a neat trick.

Of course PS effect might seem subtle or even useless compared to state of the art denoising and sharpening programs, but it's another approach / philosophy that is interesting too, and if you absolutely don't want false details AI software is not the best idea