Hi,
My impression is that the binning is done in hardware and it is patented.
Because the pixels are in a bayer pattern you cannot just bin four pixels into one, becuase color information would be lost. So you need to bin red pixels with red pixels, green pixels with green pixels and blue pixels with blue pixels. Phase One has develop a smart method of doing it. It is explained on one of LLVJs videos.
It's possible to bin in software, this is what you essentially do when you downscale the image. Read noise is not affected by software binning, so it is not as good as hardware binning.
Best regards
Erik
Just wondering about this ... and had been looking for pixel binning software. Probably for a bunch of reasons it's not commonly done ... but lots of info on astronomical and microscopy sites make reference to pixel binning being easy with CCD sensors...