Think film for a moment. Back in those wonderful days of perfect color (cough), you had your choice of Fujifilm color or Kodak color. Maybe Agfa color and a few variations on the Big Two's colors, as well. Camera makers had no say in the matter. There were no controls on a camera that could change the color you ended up with.
Digital, of course, changed all that. Someone had to pick the filtration for the Bayer layer, which impacted color, and someone had to figure out how to demosaic (convert) the raw data into color RGB pixels. The sensor/demosaic choices dictated a color palette, and further camera controls (contrast, saturation, white balance, etc.) then gave you even more choices.
Early on in digital DSLRs, we had three very distinct color choices: Fujifilm, Canon, and Nikon all went different routes with their early decisions regarding color. Fujifilm was known for a double hue shift (greens and reds shifted towards yellow), Canon for a red/orange emphasis, and Nikon for a coldly neutral, perhaps with a bit too much magenta.
Over time, however, we've slowly seen the makers on a convergence path. This was partly caused by all the testing we do these days. DxO and Imatest are happy to report color divergence errors to known targets. The assumption is that if the camera reproduces a test target color wrong, there's something wrong with its colors. Frankly, I'm all for that, as starting with dead on neutral colors and making changes is easier than starting with colors that are off and trying to make changes. Put another way, I want to control color, not let my camera maker dictate it.
Not that there aren't still small color differences between the makers. Nikon's choice of Standard for Picture Control is actually a small shift from neutral. Fortunately, they provide a Neutral Picture Control, too. But one thing I've noticed is that the differences have slowly been reducing between makers. Some of this is common use of sensors (same Bayer filtration), some is the dread of getting dinged for not being color accurate in lab tests by organizations reporting to potential buyers, some is probably just a better understanding of how to control color correctly.
So I have to ask myself: what's the point, then, of camera makers not sharing information on how to convert a raw file to match in camera JPEGs? Indeed, either way I can't understand the point of non-disclosure:
- Highly Proprietary Color (e.g. Fujifilm's double-hue shift): if 90% of users are using other raw converters, then 90% of your raw users aren't getting your proprietary color!
- Neutral Non-Proprietary Color (e.g. Nikon's Neutral Picture Control): why make it difficult for someone to get non-proprietary results? That's just making life difficult for your customer.
Of course, part of the answer is "we want to sell you something else." In Nikon's case, that would be Capture NX2. In other words, "if we make it hard for others to do, you'll have to buy our software product." Yeah, that goes over well with customers: force them to do something they don't want to do. Then don't update the product to 64-bit or current operating systems in a timely fashion and make them feel even more pain. Doesn't exactly make for happy customers, does it?
Frankly, we're at the point now where the camera companies need to make a choice (or choose both): clearly proprietary color or neutral color. And either way, as I note above, it makes full sense to disclose exactly what that is and how it is achieved.
Small footnote: I use cameras from at least five camera makers. Ever notice that you can tell which camera I used from what I post? No, didn't think so. I have my own values when it comes to color, and I process to those, not something dictated to me by a camera manufacturer.