Remedy for different skin tones on face

The outside of my face is a darker colour than the middle which is quite light and bright, they seem to blend in somewhat and dont show up in pictures much but it bothers me that I notice it everytime I look in the mirror. Other than this my skin is pretty good, I have normal skin, no acne or spot problems either. OI cleanse and moisturise twice a day, tone in the morning.

Has anyone ever had this problem? And what would you recommend I do? Thanks x