In any case I love the image quality I am getting from my A900, and the noise cleans up very well in Neat Image
Doug,
let's make something clear: I have nothing for or against the A900; I am neutral even towards my own camera (in fact the only reason I have that is, that I have a much larger investment in lenses). I have no reason to make the A900 appear better or worse than it is; my interest is purely professional. I am analyzing raw images from dozens of camera models several hours long a day, and the A900 is something special.
Now back to the question if this is done in the A/D circuitry or later. Again this question is irrelevant regarding the validity of my assertions, but it is 9an interesting question.
It is simple to say that this is done by the A/D converter, but you have to think about details: what exactly is done.
1. Action on five levels, selectable from outside.
2. Performing a different action (this is the sixth version, much different from the others) on every second pixel: the A/D is column oriented, and every second pixel is green in every column. The green pixels are treated very differently from the others.
3. Watching the
neighboring column's A/D converter: the blobs are not column or row oriented but twodimensional, context sensitive.
This is such an honorous task that Sony could have implemented a much better electronics, like some MFDBs have, still much cheaper. On the other hand, this is nothing special for the on-board processor. This may be hardware (i.e. not replacable by firmware version), but that is a far cry from being done by the A/D converter.
Those knowing how exactly such circuitries are implemented may have a different opinion, and I would not dispute that
after they have considered the above points.