Half-dead and travelling dead pixels

Posted by Pierre Igot in: Macintosh
January 28th, 2004 • 4:11 am

My 23″ Apple Cinema Display HD has 1920×1200 = 2.3 million pixels. With such a high number of individual pixels, it was probably unavoidable that I would get at least a few dead ones — if not right away, then maybe over time.

When I got the display nearly two years ago, I noticed one right away — and it’s still there today. But it is a strange kind of dead pixel. It is near the top-left corner of the screen, but it is not visible at all if the entire screen is a dark color. It only becomes visible — as a bright white pixel — if the vertical line of pixels that contains it also contains a fairly large range of white or light-coloured pixels.

For example, my desktop picture is fairly dark, but if my desktop is empty and only the picture is visible, then I cannot see the dead pixel. If, however, I open a Finder window, which typically has a fair amount of white background, and if I place the window under the dead pixel (I know where it is), so that the window’s white background covers part of the vertical line containing the dead pixel, then the dead pixel becomes apparent. And the more white there is in the line, the brighter the pixel becomes.

It’s rather strange, but it also means that this dead pixel is not as annoying as a really dead pixel would be. For example, if I am playing a video game with a black or dark background, unless there is lots of light-coloured stuff in the vertical line containing the pixel, I can’t see it. As well, if the light-coloured stuff covers the location of the dead pixel, I won’t see it either, since it’s more or less the same colour. So it’s not so bad.

Recently, however, I have started noticing another dead pixel — this time one that’s always visible on a dark background. But the funny thing is that it’s not always in the same location. It seems to be travelling. Right now it in the exact middle of the screen, but other days is more to the right and lower down. I am hoping that it means that it’s just a temporary thing. It also is not visible when my screen saver (Cosmos) is on, or when the login dialog appears after I come back to the computer and asks for my password before letting me out of screen saver mode. This login dialog is on a solid black background, and the location where the dead pixel is is definitely black — even though the screen itself is not turned off, since the login dialog is visible.

I’ve tried “massaging” both dead pixels several times, but it doesn’t make them go away.

I can’t help but wonder if this has anything to do with the rather extreme cold temperatures we’ve been experiencing lately here in eastern Canada. My office is heated as part of the whole house, of course, but its average temperature is probably lower than usual. I guess we’ll see when temperatures go back up.

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