Upload & Sell: On
dennishh, you can't 'fix' colour in output.
Part of the deal is the fine balance between microcontrast and 'microcolour', you can look this up if interested, or I can provide copious references, as the issue has a history decades long and has been discussed at great length.
You can, kind of anyway, match a given lens's output to that of one with better colour performance, but (i) you still need a reference; and (ii) why make all that extra effort if either (a) you don't see and your clients don't need it, or (b) you don't care for it as much as other characteristics, like crack sharpness. A bit like an art forgery when you think about it...
And it's not for a lot of folks, who just want a good base to do things like use 'Kodachrome presets' with, or produce B&W, etc.
It's great you did this for us as this is the essence of the alt forum - the imaging - but I must say the same differences are there with the Sigma image above. Sometimes it's subtle like a light breeze, other times not so much. Thanks for the work and comments.