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Image retention on Apple iMac

One of the main computers I use for all my work is a late 2014 5K Retina iMac. I bought it fully loaded when it first came out and it has served me well over the years. Except for one thing… the display.

Apple’s 5K displays are stunning, definitely the best display I’ve personally ever used and after getting used to the iMac it’s hard to enjoy any other monitor with a lower resolution. But even since I first got my iMac it suffered from terrible image retention. Any window that was left on the screen for more than 5-10 minutes would “burn-in” on the screen and after switching windows you would still see a ghost effect of the previous window, especially around the edges of the screen. I took my iMac to Apple and they replaced the display under warranty which made things better for a while, but eventually the issue returned and my warranty expired.

What is image retention and why does it happen?

The iMac uses a built-in Retina LCD display. To display images the pixels in an LCD display need voltage to be applied and when this happens, the pixels rearrange themselves to block certain light waves. When you have the same image on your screen for an extended period of time, the pixels remain in the same position even after your image on the screen has changed, causing image retention.

It’s also important to note that the terms “image retention” and “screen burn-in” are often used interchangeably, but they’re not the same thing. Image retention is temporary and goes away after a while, which is exactly what my iMac is doing. Screen burn-in, more common with OLED panels, on the other hand is permanent.

How to fix image retention on iMac and Apple displays?

For a long time I assumed I was out of luck regarding my issue and just had to live with it. That was until I discovered Black Light. Black Light is an application for macOS that allows you to manually change the gamma curve of your display. That sounds a little cryptic, and in our case the only feature that we’re using is the “Dim screen” option. Checking the Dim Screen setting with the lightest setting has eliminated image retention on my iMac almost completely. It does dim the screen (duh) but you can easily increase the brightness on your keyboard to compensate for the dimming effect. With this you get the same brightness level you’ve always had with the exception that image retention is now gone. Just keep in mind that if you’re doing color correction or similar work it’s best to disable Black Light.