I had a dead pixel on my iPhone a while ago. Finally, I got to the Apple store to see if they could fix it or replace it. To my surprised, it did not show up anymore. The Apple Genius asked me if I had updated my iPhone recently and that was the case. Seems that in some cases, just resetting your device can fix a dead/stuck pixel.
1- backup your device
2- try a shutdown/reboot of your device holding the sleep button. If it does not do the trick, continue with next step
3- connect your device to iTunes, and set as a new device, wiping everything...
4- check for the dead pixel. If you're lucky, it should be gone
5- restore your device with your backup
In my case, without knowing it, it solved my problem. I don't know if its the dfu mode, or starting from scratch, but it worked. Of course, this will work with a stuck pixel. If it is really dead, Apple Store is your next destination...
VicoPad addict!