The auto-enhance began with the most updated iOS app, but will likely expand to other operating systems in the near future.
Facebook seems to think that if your picture needs some help in the brightness or contrast areas, it can do a pretty good job at helping you out. The first time you upload an image, Facebook will give you a pop-up message letting you know it's being enhanced.
When an image might require auto-enhance, a small wand will appear in the lower-left of your app, allowing you to adjust the enhancement or even turn it off.
If you don't like Facebook messing with your photos, you can turn off the "Enhance Automatically" setting forever.
Source:
Digits
Written by: Andre Yoskowitz @ 19 Dec 2014 1:07