No, I don’t think it would increase noise levels. The number of pixels the sensor captures remains the same, the resolution is cut to 1/th. Each individual pixe

No, I don’t think it would increase noise levels. The number of pixels the sensor captures remains the same, the resolution is cut to 1/th. Each individual pixel in the final image will be some sort of combination of the respective, superimposed pixels. In naive averaging, a noisy pixel would lead to a larger but less prominent artifact. That, already, is close to what noise reduction in post-production does. And I can’t think of a reason not to cut outliers altogether, which would eliminate noise.