Having a single black pixel glaring at you when viewing certain background colors can be a bit frustrating and puzzling at the same time. Is it just stuck or is it dead? Today’s SuperUser Q&A post has the answer to a curious reader’s question.

Today’s Question & Answer session comes to us courtesy of SuperUser—a subdivision of Stack Exchange, a community-driven grouping of Q&A web sites.

Photo courtesy of Daniel Mogford (Flickr).

The Question

SuperUser reader Mirkan wants to know if a black pixel seen only when viewing a blue background is stuck or dead:

Is this a case of a stuck pixel or a dead one?

Is this pixel stuck or dead?

The Answer

SuperUser contributor Tetsujin has the answer for us:

Have something to add to the explanation? Sound off in the comments. Want to read more answers from other tech-savvy Stack Exchange users? Check out the full discussion thread here.

The reason the dead spot is visible only when blue is displayed is because it is a blue sub-pixel that is dead. When the background is blue, that is the only color on and it stands out. When the background is another color, the other sub-pixels reproduce it or it is still bright and absent blue, which is less noticeable.

For example, you can see yellow because it is created from red plus green. A white pixel with a dead blue sub-pixel will produce yellow, which is not very noticeable in a bright spot that small.