With time to spare today I wanted to see the real effects of adjusting these values in the menu to see the effect on the jpeg output. I think an image speaks a thousand words on this subject so please if you were interested/curious and don't have enough time to try yourself you can see the results here and download the jpegs as a reference:
Although tested on my X Pro 1 (odd I never pick up the X-T1 for this stuff) it will apply to the current crop of Fuji cameras. At least until tomorrow!