Oh, the green tint in backdrop was done using 'selective color' tool in Photoshop (Image → Adjustments → Selective Color)
What we need to adjust is the color in 'highlight' range (the brightest of all color in the picture) - mostly white color. We want to make it look green instead of white.
So you go to the said menu, and select the 'white' from drop down menu, then increase Cyan value, drop Magenta, and add more 'Black' to it.
Pic for better understanding:
Just play around with the sliders values and you might accidentally fine the combination you like! (Like I always did)