Im not sure by the photo what your referring too but If its a loss in detail in the shadows and highlights than you may want to run Apple's calibration. System Preferences > Displays > Color > Calibration.

---

MOBO: Z77MX-QUO-AOS CPU: Core i7 3770K GPU: MSI N760 TF 2GD5/OC Case: Modded MacPro2,1
Memory: 32GB Corsair Vengeance (CMY32GX3M4A1600C9) Wifi: Airport Extreme bcm94321MCA BIOS: HermitCrab Labs H3A.816M
Monitor: AOC Q2963Pm 29" WFHD 2560x1080 21:9
Interests: KDE on Apple Darwin, Keeping it real with the command line, Helping those that help themselves