I just wanted to be sure people saw this post. It's an Xposed module that turns on the S5 Power Saving Mode, it turns everything to grayscale.
http://xdaforums.com/galaxy-note-3/themes-apps/xposed-s5-power-saving-mode-t2814113
http://xdaforums.com/galaxy-note-3/themes-apps/xposed-s5-power-saving-mode-t2814113