I use [Ifranview](http://www.irfanview.com/) for a lot of quick graphical tasks.  Among its features is the ability to "Auto Correct Colors" (Shift U).

I don't rely on this feature, preferring to do this manually, but sometimes I apply it because I am curious to see what adjustments it will make.

Today I applied it to a black and white image, and lo and behold, it recreated the gold colors of the background.

Question: how does it know what the original colors were? Is this color information somehow saved in the file?

Here's the black and white, and the auto-corrected version next.

Gallery