MacBook Pros and External Displays

Today, I hooked a newly purchased display to my MBP. (Looks like they’re out of stock right now, but it was $80 for 24″ when I bought it last week.) This isn’t intended to be my display. It’s replacing an old 14″ monitor for a kid. I thought I’d just steal it now and then during the day. It’s extremely lightweight and easy to move between rooms.

What I didn’t expect was how awful the text looked on it. I hooked up the monitor to the MBP using my Apple TV HDMI cable. The text was unreadable. I use similar TV-style monitors for my main system and they display text just fine. However, I’m using normal display ports and cables for my mini. This is the first time I’ve gone HDMI direct.

So off to websearch I went. Sure enough this is a known longstanding problem that many people have dealt with before. The MBP sees the TV as a TV and not a monitor. It produces a YUV signal instead of the RGB signal that improves text crispness. Pictures look pretty, text looks bad.

All the searches lead to this ruby script. The script builds a display override file containing a vendor and product ID with 4:4:4 RGB color support. The trick lies in getting macOS to install, read, and use it properly. That’s because you can’t install the file directly to /System/Library/Displays/Contents/Resources/Overrides/ in modern macOS. Instead, you have to disable “rootless”.

I wasn’t really happy about going into recovery mode. Disabling system integrity protection feels like overkill for a simple display issue. But it  worked.  It really only took a few minutes to resolve once I convinced myself it was worth doing. If you have any warnings and cautions about installing custom display overrides, please let me know. It  feels like I did something morally wrong even if it did fix my problem.

My external display went from being unusable to merely imperfect. The text is still a bit blurry but you can read it without inducing a migraine. Not nearly as crisp as normal display ports (which looks fine when used with this monitor) but I don’t have to buy a new cable and I don’t plan to use this much.

If I were going to use this monitor regularly with the MBP, I’d definitely purchase a proper cable. As it is, I’m happy enough to have found a workable-ish solution. The monitor is quite nice especially in “shop mode”, and has so far worked well with Chromecast, AppleTV, and Wii.


  • […] Erica Sadun: […]

  • I did the same thing recently, but bought an Apple Cinema Display (20″ 1680×1050 : 2004) at Goodwill and hooked it up with my MBP when the screen went out. They have them on ebay for around $70, exactly what I paid. Anyway, they are nice sceens and larger although a little darker than the backlit screens originally on my MBP.

  • Why didn’t you just buy a proper TV/Monitor? I know you can cut spendings and all, but is it really worth your time, hassle and potential strain of your eyes?

    • Why? For $88. For a monitor that’s primarily going to be used by my kids. And one that will be connected with a normal cable for normal use. When I steal it during the day (when the kids are not off school), then I can use it as an extra monitor. Win!

      So far, it’s been used with a MBP, with a Wii system, and Chromecast. We are getting great value out of this thing.