You need to find the VAIO Control Center and go to Image Quality controls. Then look for an on/off button for the feature and turn it off.
The VAIO Control Center can be accessed from the start button on the Home Screen or search for VAIO Control Center and you should find it. Open up Search by keying the Windows Key + S.
Step 2: Turn Off Auto-Brightness in the Intel HD Graphics Control Panel
The Intel HD Graphics Control panel can be found by searching the control panel, this is done by pressing Windows + S.
Once the control panel comes up, you'll need find the Power management panel. Then click on the battery controls.
Turn Off Display Power Saving Technology
Good luck!