Hello, first thanks for your work developing and maintaining xcalib.
When I have to use Windows I use NegativeScreen to invert the colors. One feature that I really enjoy is smart invert which they describe as such:
Different inversion modes are provided, including “smart” modes, allowing blacks and whites inversion, while keeping colors (about) the sames.
The feature really shines when browsing the web. It looks closer towards a true universal dark theme than anything else I've seen. For example here is the duckduckgo homepage:

From a linux system if you look at the the same page after applying xcalib -invert -alter the logo appears to be more bluish and has a less native feel to it. This effect, of course, carries over to the rest of the web and whatever UI is in use.
I was wondering how difficult would it be to create either a smart invert function and/or an icc profile for xcalib?
The inversion matrices can be found here.
I'd appreciate hearing any thoughts you have on this subject.
Thanks again!