There is an anomaly in the period b/w photo that nobody wants to mention, it's like the elephant in the room. Though can't blame the members here, since the example posted has had the contrast dialed up:
Not sure what the lighter vertical stripe is down the middle (could be a scan from a book and and the back page is showing through), but what needs to be focused on is the gradation occurring towards the right side of the picture. Not only is the tail section darker, but so is the background - ground, trees and sky.
I'm in the camp with the standard factory finish colours.
regards,
Jack