Logo 61e73bc61c0e1780102320e879dc3cac0e29303ea8894dd8f10c942f3ba8120f


An adorable little blog

Dell UltraSharp

Thursday — April 6th, 2017

Dell ultrasharp display I've been enjoying Dell's 25" UltraSharp U2515H display for the past few months. It has excellent color accuracy, a bright backlight, and great resolution for the price.

I’ve noticed one oddity though, the display produces a strange dithering effect on shadows and blurs in macOS Sierra.

Dithering More of the dithering

The issue seems to be in the display's presentation of the image, and not the image itself. Screenshots captured from the OS, like the one below, don't show the dithering.

Screenshot without dithering

It took me a week before I could pin down the issue. It appears to be a bug with either the display or my old Mac mini's handling of DisplayPort 1.2. The fix is simple enough, disable DisplayPort 1.2 in the monitor's settings menu and the blurs and shadows show as expected.

To disable this setting, tap on the menu button (third from the left) to bring up the display’s configuration menu.

Menu button

Next, navigate down to the Display section on the left hand side using the down-arrow (second button from the right). Then use the right-arrow (third-button from the right) to navigate to the right panel. Select the DP 1.2 setting using the right-arrow and set it to Disable and confirm.

Display menu
Confirm display settings change

Now blurs and shadows render as you would expect. No more weird dithering.

Display dithering fixed

I can't remember if this is something I turned on out of stupidity or if the display comes from the factory with this setting.

Either way, I hope this can save someone else the headache.