And should adjusting the curve for example keep things as neutral greys? It should. Are you seeing something different?
And should adjusting the curve for example keep things as neutral greys?
If this works, one could start testing which color space has the behaviour in Aperture (hint: it's not Adobe RGB). I was under the impression the underling color space used for processing in Aperture was Adobe RGB but for whatever reason, Apple doesn't want to tell us what exactly is happening under the hood. What makes you say its not Adobe RGB (perhaps using a linear TRC)?
If this works, one could start testing which color space has the behaviour in Aperture (hint: it's not Adobe RGB).