From the artist:  
“I have to say right now; I’ve seen many other much better humanized versions of these characters around DA, but it’s still fun to give it a go, right?
 
I tried to take the colors from the characters and use them here, like everyone has (duh).  
But the colors of their skin was a little difficult.  
Celestia has been much more out in the sun that Luna, and Luna spend most of her time on the moon, with little to no light at all.  
So, it’s with no question to say who got more color in their skin. xD
 
Also, for the hair? I don’t think many ‘humans’ would walk around with so cartoon-colorful hair, and it would feel “too easy” to just copy paste all the colors onto the human versions.
 
So, I tried a little of this and that with these two. Again, I’ve seen many better versions out there, but it was fun to give it my own take!
 
It was pretty quickly sketched up and colored, so I may make an updated version later.”