Trying to change brightness on my desktop screens via powershell and encountered an error

Question

Trying to change brightness on my desktop screens via powershell and encountered an error

דרור פרוחי 5

Hello,

I want to change the brightness of my screens (I have two screens) on my desktop computer using PowerShell. I use this command:

(Get-WmiObject -namespace root/wmi -class WmiMonitorBrightnessMethods).wmisetvrightness(1,20)

and I get an error :

Get-WmiObject : Not supported
At line:1 char:2
+ (Get-WmiObject -namespace root/wmi -class WmiMonitorBrightnessMethods ...
+  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : InvalidOperation: (:) [Get-WmiObject], ManagementException
    + FullyQualifiedErrorId : GetWMIManagementException,Microsoft.PowerShell.Commands.GetWmiObjectCommand

You cannot call a method on a null-valued expression.
At line:1 char:1
+ (Get-WmiObject -namespace root/wmi -class WmiMonitorBrightnessMethods ...
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : InvalidOperation: (:) [], RuntimeException
    + FullyQualifiedErrorId : InvokeMethodOnNull

I use the same command on my laptop and it works.

I would like to know why I get this error and how to fix it.

I know that my computer does not programmatically support changing the brightness and I know that there are free third-party programs that perform this operation, yet I want to understand how they do it and what command those programs use.

I ask because I want to build software that reduces screen brightness.

CK 106 Reputation points

2023-08-18T05:24:56.2933333+00:00

BTW looks to be a typo in your command, the 'v' should be a 'b'!

(Get-WmiObject -namespace root/wmi -class WmiMonitorBrightnessMethods).wmisetvrightness(1,20)

Correct command:

(Get-WmiObject -namespace root/wmi -class WmiMonitorBrightnessMethods).wmisetbrightness(1,20)
CK 106 Reputation points

2023-08-18T05:31:36.43+00:00

Also, check if PS can see your external monitors - mine can only see the laptop screen:

^ Laptop monitor
Avil 0 Reputation points

2023-10-12T11:43:31.4166667+00:00
Hi, I've done:

Get-WmiObject -Namespace root/WMI -Class WmiMonitorBrightnessMethods | foreach {write-output $_}

and found that it only picks up my one monitor.

Do you know how to enlighten powershell to my other monitor?

3 answers

Your answer

CK 106 Reputation points

2023-08-18T05:24:56.2933333+00:00

BTW looks to be a typo in your command, the 'v' should be a 'b'!

(Get-WmiObject -namespace root/wmi -class WmiMonitorBrightnessMethods).wmisetvrightness(1,20)

Correct command:

(Get-WmiObject -namespace root/wmi -class WmiMonitorBrightnessMethods).wmisetbrightness(1,20)
CK 106 Reputation points

2023-08-18T05:31:36.43+00:00

Also, check if PS can see your external monitors - mine can only see the laptop screen:

^ Laptop monitor
Avil 0 Reputation points

2023-10-12T11:43:31.4166667+00:00

Hi, I've done:

Get-WmiObject -Namespace root/WMI -Class WmiMonitorBrightnessMethods | foreach {write-output $_}

and found that it only picks up my one monitor.

Do you know how to enlighten powershell to my other monitor?

Answer 1

Rich Matheisen 48,116

Are you running Windows Powershell 5, or the multi-platform PowerShell 7? WMI isn't part of PowerShell 7.

0 comments

Answer 2

Castorix31 91,871

I know that my computer does not programmatically support changing the brightness and I know that there are free third-party programs that perform this operation, yet I want to understand how they do it and what command those programs use.

It can be done with GetVCPFeatureAndVCPFeatureReply / SetVCPFeature

Brightness is 0x10 code (you can test codes with ClickMonitorDDC tool)

0 comments

Answer 3

MotoX80 37,686

If you have 2 monitors, then the WMI call is probably returning 2 objects.

Try this.

Get-WmiObject -namespace root/wmi -class WmiMonitorBrightnessMethods | foreach {
    $_.wmisetbrightness(80,20)
}

דרור פרוחי 5

Thanks for the quick reply

I tried to execute the code you sent me and I got this error:

Get-WmiObject : Not supported
At line:1 char:1
+ Get-WmiObject -namespace root/wmi -class WmiMonitorBrightnessMethods  ...
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : InvalidOperation: (:) [Get-WmiObject], ManagementException
    + FullyQualifiedErrorId : GetWMIManagementException,Microsoft.PowerShell.Commands.GetWmiObjectCommand

MotoX80 37,686 Reputation points

2023-03-16T12:30:13.9933333+00:00

In the foreach block just output $_ and see if it displays 2 objects. I don't have 2 monitors so unfortunately I can't test this.

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Trying to change brightness on my desktop screens via powershell and encountered an error

3 answers

Your answer