An XDA developer has successfully ported Sony's image processing and enhancing algorithm, X-Reality Engine for Mobile, to work on lower-end Xperia Smartphones. Previously, X-Reality was only available to high-end Sony mobiles such as the Xperia Z1, Xperia Z Ultra, Xperia Z1S and Xperia Z2.
For X-Reality to work, your device needs to be running Android 4.3 or higher. It works with locked and unlocked bootloaders; your device needs to be rooted.
Here's the detailed guide. Mind you, it is pretty complicated.