yes you described the issue very well . i am facing the exact same problem on my device . did you try this app
if you tried it please give me feed back .
and do you have any information about a new update or something from sony trying to solve this issue ?!
And frankly the app is useless. The method described by hitman1376 is the best calibration process but unfortunately the bug is in the system/rom itself and no amount of calibration can remove the bug unless a new update is provided by sony.
Regarding the update, the only thing we can do is hope and wait