Washed out external monitor on M1 Mac mini on usb c

Hello, David Oldenburg!

Thanks for reaching out in Apple Support Communities! From your post, it sounds like you're having trouble with the video on your external monitor when connected to your Mac. We'd like to help out!

Does this happen when you use a different USB-C cable or when the same monitor is connected via HDMI?

If so, we recommend using the troubleshooting steps to help with video related issues as described in the support article below:

Get help with video issues on external displays connected to your Mac - Apple Support

"If you've tried these steps and your display still isn't working, contact Apple Support to get more help."

All the best.

Same issue here.

Mac mini (M1, 2020) 8GB Big Sur Ver. 11.2.2 connected to two LG 27UK670-B monitors.

When connected through USB-C colors are totally washed out. Blacks look grey, and colors look like I'm viewing through parchment paper. Also, updating to 11.2.2 did NOT fix the issue.

However, with the same M1 Mac Mini connected via HDMI blacks are deeper, and colors pop.

For comparison I connected my 2018 Intel Macbook Pro 15" (Big Sur Ver. 11.2.2) to the same monitors using USB-C connections. The colors are rich and punchy.

Hopefully Apple is reading this forum and putting together a fix.

1. Connected to charger all along via my dock
2. HDR is turned off.
3. I can connect to HDMI with no change in cable or settings. Full colors, but 30Hz.
4. Yes. Big Sur 11.3
5. Cannot change the resolution before opening the lid as I have no KBD/mouse, using the macbook's own KBD/Trackpad
6. Cables are fine as my 2016 Intel Macbook pro in the same setup does full color & full 60Hz on both DP and HDMI. I can literally take one out, plug the other in the same setup, and voila. But, 2016 intel is very slow and with constant fan when I start zoom. My M1 is really fast.
7. I am not a big video editing guy, so I can live with 30Hz as long as I get nice colors

I think it is hit or miss. My Dell 4K monitor at work does DP with full colors @60hz with no issues with this M1. It is the M1 and LG 4K combo.

I have the exact same issue... Two identical LG 4k HDR 27" monitors. The monitor connected through HDMI is contrasty and great colors, but the one through USB-C is washed out.

I have read somewhere that a USB-C to HDMI cable works well, I have ordered one and hopefully it will not be waste of $$$ :)

As long you connect to the HDMI port on the monitor, you will get great colors. I had to use HDMI->Active Display port on my Caldigit USB-Pro Dock and the dock connects to M1 pro via TB3 cable.

Can you check what refresh rate you are getting? You can check either on the monitor or About This Mac -> System Report -> Graphics/Display.

I get only 30Hz with HDMI and 60Hz via DP. My doc does not have TB input.

Setting the display to Limited Range RGB is not a solution for the majority of the users, since

• most displays do not have the option for limited range RGB in case of DisplayPort connections (limited range RGB is mostly a HDMI thing, in the early days of digital transformation content was mostly encoded with this in mind due to technical considerations and even up to this day many SDR content is treated like this - but computer monitors should always use full RGB).
• Limited range RGB actually worsens the display quality (as it can reproduce less colors) even if the dynamic range is recovered by setting the display to "RGB (Limited range)".

This problem clearly lies in MacOS.

Agree with selected9. As explained earlier in my case:

HDMI - Full color Range, but 30Hz

DisplayPort - Limited Range(maybe - don't know how to find out), but 60Hz.

on LG 4k there is an option called HDMI UltraHD Deep Color - which is on. I don't think it will apply to DisplayPort. This confirms selected9's comment that color range is mostly HDMI thing.

For me only this script worked.

It changes not only /Library/Preferences/com.apple.windowserver.displays.plist file but also one more which has external display UUID in name.

HDR = High Dynamic Range

See the screenshot in earlier messages for the location of the system setting under System Preferences -> Displays.

Sometimes randomly colors become normal, I don't know what this is connected with, I don't do anything, at some point the monitor just blinks for a second and the colors become normal.

I also noticed that in the monitor settings there is a switch which is always not available for change - "Black Level"

So that's when he's in the "LOW" position colors are washed up but

After the monitor blinks and the colors return to normal - "HIGH"

Might be LG too must develop a new firmware for their monitors, or apple just fix their drivers idk

Did you send a feedback to apple using the Feedback Assistant? I did but the ticket is still Open (after weeks) and it says that there are no "recent similar reports". I am not sure whether Apple is even aware of the issue - I feel we complain in vain in these forums.

I am using the airplay trick (with my iPad) whenever the colors go washed out. If I manage to get back the normal colors, things usually remain stable (until I change the resolution or something).

I don't think the issue is related to HDR since I experience this with a non-HDR display. It is more a displayport over USB-C problem.

External display support of M1 macs is really poor. This issue and the lack of DDC/CI support (can't control the brightness or audio volume of external displays via MonitorControl or Luna) is a real pain.

Are you connected to charger all this while ?

If available, is HDR turned off in display settings ?

Are you on Big Sur 11.3 ?

If you are on charger, the monitor display should go from being secondary monitor to primary display when you close you lid. Does the colours still stay washed out ?

Try changing resolution before opening the lid.

I tried lot of cables ( USB C to display port , different USB C cables etc ) and May other different methods as suggested by everyone. But closing lid and changing resolution and opening up again, worked for me.

Hmm. It might not be an exact science. For me the key is changing display arrangement while AirPlay is active (from mirrored to non mirrored or vice versa). But I am not using Extended display mode to begin with, I use an external display only, the macbook is in clamshell mode.

I just tried the same. Connected to DisplayPort. Went to scaled mode and enabled low resolution mode to give me choice of refresh rates. It only showed 60 and 30Hz. I tried toggling between the two. No luck. Stayed washed out on DP. So, back to HDMI @30hz and good colors.

Looks like I am stuck in this mode forever. What a shame.

Thanks for the reply, David Oldenburg.

Based on the information you've provided, we recommend you Contact Apple Support for additional troubleshooting options.

Take care.