Many times seeing a photo, I happened to like the tones of it, on this page you indicate the direction of a photo and you make a map of the 8 dominant colors.
It is interesting for layout of works and to follow a uniformity.
By the way, the same thing can be done with photoshop in 2 steps:
Image – mode – indexed color – we change the value of 256 by 8
Image – mode – color map
Finally we just have to save and we have a color map ready to use.