Tip: To verify that YPbPr is being used by your monitor, check the “Input Color Format” in the monitor settings. The details are documented by this webpage, Fixing the External Monitor Color Problem with My 2018 MacBook Pro. This is accomplished by creating or overwriting the macOS’s EDID (Extended Display Identification Data) configuration file for the Dell monitor. The solution is to force the Mac to use the RGB input color format for my Dell U2410 monitor. Online comments seem to indicate that this issue only occurs with the 2018 (and probably later) Macs. Note: I did not see this problem when connecting my MacBook Air 2015 to the Dell monitor using the Apple Mini DisplayPort to DVI adapter.
I am not sure why the Mac defaulted to using YPbPr, instead of the superior RGB color format. The Dell monitor supports two input color formats, RGB (digital computer standard) and YPbPr (analog TV standard).
The problem is caused by the Mac choosing to talk to the Dell monitor using YPbPr, an input color format previously used by S-Video and composite video for analog TVs. The text looks like it would on an old analog TV. After connecting my newly-purchased Mac mini 2018 to my Dell U2410 24 inch 1920×1200 LCD monitor by HDMI cable, I notice that the text is a little blurry and pixelated.
