Alternative pixel therapy
I have a stuck or dead pixel in the bottom-left quadrant of my iMac’s screen. I can’t remember when it first appeared, but I’ve had the iMac for nearly five years. I’ve read about various cures, such as rubbing the screen with a cloth or a pencil eraser, but that doesn’t seem to have helped, and all the software cures seem to be for Windows only. What else could I try? Matt Feine I’m afraid not. These cures are all snake oil. A dead pixel is caused by a failure of the circuitry controlling the polarisation state of the red, green and blue subpixels. This causes all of them to permanently block the light from the backlight. A stuck pixel is the same thing, except that one or more of the subpixels has failed in the opposite polarisation, so that they always let the light through. Both are caused by blown transistors. I have a stuck pixel on one of my monitors that only appears when the monitor gets hot, probably because the resistance increases with temperature and pushes a slight defect in the circuitry over some threshold. Some of the myths about dead pixel cures might have started because the time taken to carefully rub the screen allows the circuit to cool down. The only actual cure is to replace the monitor.
The huge number of pixels in modern displays increases the chance of one of them failing. But they are smaller and less obvious.