Yes, it's duplicate, but poll is easier to look at and much more convenience for other to compare when making a PSP purchase. I just hope that the mod do not lock this.
Defective pixel define as a dead pixel or stuck pixel.
A dead pixel is an unlit pixel, regardless of what color it suppose to show, it stay black.
A stuck pixel is also call, a lit pixel. It stay lit at one color regardless of what color it suppose to be.
An unlit sub-pixel is also consider as a dead pixel. Each pixel compose of three sub-pixel, R-G-B. For example, an unlit green, will shown any color, including black, but will not show green or white, and show other color that need green incorrectly