Which effect are you talking about? If it is just the color grading of it, that's a 60% opacity layer of #363e40. You can see it in the CSS as .xenith_bg_mask
Thanks. So, the actual pictures are not changed. Whatever is displayed has the same effect applied to it when displayed. There isn't unique tweaking of individual pictures. So, if I added a layer of color 363e40 with 60% opacity on top of a picture in Photoshop, it would have the same effect.