EXIF information of threat starter's image shows the following
-- Nikon D90 DSLR fitted with AF-S 18-105VR F3.5-5.6 lens
-- Aperture priority setting
-- 58mm focal length AF-C Dynamic Wide AF-Area mode with VR turned on
-- ISO800 1/13s shutter speed F5 setting (against max. aperture opening of F5.1) EV+0
-- Auto Active D-Lighting setting
-- High ISO noise reduction activated
-- Standard setting for picture control
-- Possibly auto white balance setting
At focal 58mm focal length, Photozone and SLRGear indicate better image can be obtained from F8 or F11 aperture setting.
If thread starter wishes to capture ambient light of the indoor environment, tripod mounted shot with low ISO setting, small aperture setting & slow shutter speed maybe an alternative setting to pursue instead of relying on pumping up the ISO setting.
In addition, picture lacked post processing as thread starter's picture histogram showed low contrast with pixels crowding left half of histogram distribution before processing. This possibly occurred as the camera is partially fooled by the light coloured wall. Other enhancements during post processing may include increasing lens distortion correction, colour cast correction, colour saturation and image sharpening.
Below is outcome my attempt on the post processing of thread starter image.