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How To Control Brightness Levels On Windows 10

You can manage your monitor’s brightness via the function keys on your keyboard. When you tap either the increase or decrease brightness keys, Windows 10 decreases the brightness by a certain level. There’s no way to control the brightness levels when you use the dedicated buttons. If you want finer control, you will have to use the brightness slider. If you want to control the brightness levels when you change brightness with your keyboard, you can do so with an AutoHotkey script.

SPOILER ALERT: Scroll down and watch the video tutorial at the end of this article.

Brightness Increment Levels

Make sure you have AutoHotkey installed on your system.

Open Notepad and paste the following in it. This script was written by Reddit user yet_another_usr.

class BrightnessSetter {
; qwerty12 - 27/05/17
; https://github.com/qwerty12/AutoHotkeyScripts/tree/master/LaptopBrightnessSetter
static _WM_POWERBROADCAST := 0x218, _osdHwnd := 0, hPowrprofMod := DllCall("LoadLibrary", "Str", "powrprof.dll", "Ptr")

__New() {
if (BrightnessSetter.IsOnAc(AC))
this._AC := AC
if ((this.pwrAcNotifyHandle := DllCall("RegisterPowerSettingNotification", "Ptr", A_ScriptHwnd, "Ptr", BrightnessSetter._GUID_ACDC_POWER_SOURCE(), "UInt", DEVICE_NOTIFY_WINDOW_HANDLE := 0x00000000, "Ptr"))) ; Sadly the callback passed to *PowerSettingRegister*Notification runs on a new threadl
OnMessage(this._WM_POWERBROADCAST, ((this.pwrBroadcastFunc := ObjBindMethod(this, "_On_WM_POWERBROADCAST"))))
}

__Delete() {
if (this.pwrAcNotifyHandle) {
OnMessage(BrightnessSetter._WM_POWERBROADCAST, this.pwrBroadcastFunc, 0)
,DllCall("UnregisterPowerSettingNotification", "Ptr", this.pwrAcNotifyHandle)
,this.pwrAcNotifyHandle := 0
,this.pwrBroadcastFunc := ""
}
}

SetBrightness(increment, jump := False, showOSD := True, autoDcOrAc := -1, ptrAnotherScheme := 0)
{
static PowerGetActiveScheme := DllCall("GetProcAddress", "Ptr", BrightnessSetter.hPowrprofMod, "AStr", "PowerGetActiveScheme", "Ptr")
,PowerSetActiveScheme := DllCall("GetProcAddress", "Ptr", BrightnessSetter.hPowrprofMod, "AStr", "PowerSetActiveScheme", "Ptr")
,PowerWriteACValueIndex := DllCall("GetProcAddress", "Ptr", BrightnessSetter.hPowrprofMod, "AStr", "PowerWriteACValueIndex", "Ptr")
,PowerWriteDCValueIndex := DllCall("GetProcAddress", "Ptr", BrightnessSetter.hPowrprofMod, "AStr", "PowerWriteDCValueIndex", "Ptr")
,PowerApplySettingChanges := DllCall("GetProcAddress", "Ptr", BrightnessSetter.hPowrprofMod, "AStr", "PowerApplySettingChanges", "Ptr")

if (increment == 0 && !jump) {
if (showOSD)
BrightnessSetter._ShowBrightnessOSD()
return
}

if (!ptrAnotherScheme ? DllCall(PowerGetActiveScheme, "Ptr", 0, "Ptr*", currSchemeGuid, "UInt") == 0 : DllCall("powrprof\PowerDuplicateScheme", "Ptr", 0, "Ptr", ptrAnotherScheme, "Ptr*", currSchemeGuid, "UInt") == 0) {
if (autoDcOrAc == -1) {
if (this != BrightnessSetter) {
AC := this._AC
} else {
if (!BrightnessSetter.IsOnAc(AC)) {
DllCall("LocalFree", "Ptr", currSchemeGuid, "Ptr")
return
}
}
} else {
AC := !!autoDcOrAc
}

currBrightness := 0
if (jump || BrightnessSetter._GetCurrentBrightness(currSchemeGuid, AC, currBrightness)) {
maxBrightness := BrightnessSetter.GetMaxBrightness()
,minBrightness := BrightnessSetter.GetMinBrightness()

if (jump || !((currBrightness == maxBrightness && increment > 0) || (currBrightness == minBrightness && increment < minBrightness))) {
if (currBrightness + increment > maxBrightness)
increment := maxBrightness
else if (currBrightness + increment < minBrightness)
increment := minBrightness
else
increment += currBrightness

if (DllCall(AC ? PowerWriteACValueIndex : PowerWriteDCValueIndex, "Ptr", 0, "Ptr", currSchemeGuid, "Ptr", BrightnessSetter._GUID_VIDEO_SUBGROUP(), "Ptr", BrightnessSetter._GUID_DEVICE_POWER_POLICY_VIDEO_BRIGHTNESS(), "UInt", increment, "UInt") == 0) {
; PowerApplySettingChanges is undocumented and exists only in Windows 8+. Since both the Power control panel and the brightness slider use this, we'll do the same, but fallback to PowerSetActiveScheme if on Windows 7 or something
if (!PowerApplySettingChanges || DllCall(PowerApplySettingChanges, "Ptr", BrightnessSetter._GUID_VIDEO_SUBGROUP(), "Ptr", BrightnessSetter._GUID_DEVICE_POWER_POLICY_VIDEO_BRIGHTNESS(), "UInt") != 0)
DllCall(PowerSetActiveScheme, "Ptr", 0, "Ptr", currSchemeGuid, "UInt")
}
}

if (showOSD)
BrightnessSetter._ShowBrightnessOSD()
}
DllCall("LocalFree", "Ptr", currSchemeGuid, "Ptr")
}
}

IsOnAc(ByRef acStatus)
{
static SystemPowerStatus
if (!VarSetCapacity(SystemPowerStatus))
VarSetCapacity(SystemPowerStatus, 12)

if (DllCall("GetSystemPowerStatus", "Ptr", &SystemPowerStatus)) {
acStatus := NumGet(SystemPowerStatus, 0, "UChar") == 1
return True
}

return False
}

GetDefaultBrightnessIncrement()
{
static ret := 10
DllCall("powrprof\PowerReadValueIncrement", "Ptr", BrightnessSetter._GUID_VIDEO_SUBGROUP(), "Ptr", BrightnessSetter._GUID_DEVICE_POWER_POLICY_VIDEO_BRIGHTNESS(), "UInt*", ret, "UInt")
return ret
}

GetMinBrightness()
{
static ret := -1
if (ret == -1)
if (DllCall("powrprof\PowerReadValueMin", "Ptr", BrightnessSetter._GUID_VIDEO_SUBGROUP(), "Ptr", BrightnessSetter._GUID_DEVICE_POWER_POLICY_VIDEO_BRIGHTNESS(), "UInt*", ret, "UInt"))
ret := 0
return ret
}

GetMaxBrightness()
{
static ret := -1
if (ret == -1)
if (DllCall("powrprof\PowerReadValueMax", "Ptr", BrightnessSetter._GUID_VIDEO_SUBGROUP(), "Ptr", BrightnessSetter._GUID_DEVICE_POWER_POLICY_VIDEO_BRIGHTNESS(), "UInt*", ret, "UInt"))
ret := 100
return ret
}

_GetCurrentBrightness(schemeGuid, AC, ByRef currBrightness)
{
static PowerReadACValueIndex := DllCall("GetProcAddress", "Ptr", BrightnessSetter.hPowrprofMod, "AStr", "PowerReadACValueIndex", "Ptr")
,PowerReadDCValueIndex := DllCall("GetProcAddress", "Ptr", BrightnessSetter.hPowrprofMod, "AStr", "PowerReadDCValueIndex", "Ptr")
return DllCall(AC ? PowerReadACValueIndex : PowerReadDCValueIndex, "Ptr", 0, "Ptr", schemeGuid, "Ptr", BrightnessSetter._GUID_VIDEO_SUBGROUP(), "Ptr", BrightnessSetter._GUID_DEVICE_POWER_POLICY_VIDEO_BRIGHTNESS(), "UInt*", currBrightness, "UInt") == 0
}

_ShowBrightnessOSD()
{
static PostMessagePtr := DllCall("GetProcAddress", "Ptr", DllCall("GetModuleHandle", "Str", "user32.dll", "Ptr"), "AStr", A_IsUnicode ? "PostMessageW" : "PostMessageA", "Ptr")
,WM_SHELLHOOK := DllCall("RegisterWindowMessage", "Str", "SHELLHOOK", "UInt")
if A_OSVersion in WIN_VISTA,WIN_7
return
BrightnessSetter._RealiseOSDWindowIfNeeded()
; Thanks to YashMaster @ https://github.com/YashMaster/Tweaky/blob/master/Tweaky/BrightnessHandler.h for realising this could be done:
if (BrightnessSetter._osdHwnd)
DllCall(PostMessagePtr, "Ptr", BrightnessSetter._osdHwnd, "UInt", WM_SHELLHOOK, "Ptr", 0x37, "Ptr", 0)
}

_RealiseOSDWindowIfNeeded()
{
static IsWindow := DllCall("GetProcAddress", "Ptr", DllCall("GetModuleHandle", "Str", "user32.dll", "Ptr"), "AStr", "IsWindow", "Ptr")
if (!DllCall(IsWindow, "Ptr", BrightnessSetter._osdHwnd) && !BrightnessSetter._FindAndSetOSDWindow()) {
BrightnessSetter._osdHwnd := 0
try if ((shellProvider := ComObjCreate("{C2F03A33-21F5-47FA-B4BB-156362A2F239}", "{00000000-0000-0000-C000-000000000046}"))) {
try if ((flyoutDisp := ComObjQuery(shellProvider, "{41f9d2fb-7834-4ab6-8b1b-73e74064b465}", "{41f9d2fb-7834-4ab6-8b1b-73e74064b465}"))) {
DllCall(NumGet(NumGet(flyoutDisp+0)+3*A_PtrSize), "Ptr", flyoutDisp, "Int", 0, "UInt", 0)
,ObjRelease(flyoutDisp)
}
ObjRelease(shellProvider)
if (BrightnessSetter._FindAndSetOSDWindow())
return
}
; who knows if the SID & IID above will work for future versions of Windows 10 (or Windows 8). Fall back to this if needs must
Loop 2 {
SendEvent {Volume_Mute 2}
if (BrightnessSetter._FindAndSetOSDWindow())
return
Sleep 100
}
}
}

_FindAndSetOSDWindow()
{
static FindWindow := DllCall("GetProcAddress", "Ptr", DllCall("GetModuleHandle", "Str", "user32.dll", "Ptr"), "AStr", A_IsUnicode ? "FindWindowW" : "FindWindowA", "Ptr")
return !!((BrightnessSetter._osdHwnd := DllCall(FindWindow, "Str", "NativeHWNDHost", "Str", "", "Ptr")))
}

_On_WM_POWERBROADCAST(wParam, lParam)
{
;OutputDebug % &this
if (wParam == 0x8013 && lParam && NumGet(lParam+0, 0, "UInt") == NumGet(BrightnessSetter._GUID_ACDC_POWER_SOURCE()+0, 0, "UInt")) { ; PBT_POWERSETTINGCHANGE and a lazy comparison
this._AC := NumGet(lParam+0, 20, "UChar") == 0
return True
}
}

_GUID_VIDEO_SUBGROUP()
{
static GUID_VIDEO_SUBGROUP__
if (!VarSetCapacity(GUID_VIDEO_SUBGROUP__)) {
VarSetCapacity(GUID_VIDEO_SUBGROUP__, 16)
,NumPut(0x7516B95F, GUID_VIDEO_SUBGROUP__, 0, "UInt"), NumPut(0x4464F776, GUID_VIDEO_SUBGROUP__, 4, "UInt")
,NumPut(0x1606538C, GUID_VIDEO_SUBGROUP__, 8, "UInt"), NumPut(0x99CC407F, GUID_VIDEO_SUBGROUP__, 12, "UInt")
}
return &GUID_VIDEO_SUBGROUP__
}

_GUID_DEVICE_POWER_POLICY_VIDEO_BRIGHTNESS()
{
static GUID_DEVICE_POWER_POLICY_VIDEO_BRIGHTNESS__
if (!VarSetCapacity(GUID_DEVICE_POWER_POLICY_VIDEO_BRIGHTNESS__)) {
VarSetCapacity(GUID_DEVICE_POWER_POLICY_VIDEO_BRIGHTNESS__, 16)
,NumPut(0xADED5E82, GUID_DEVICE_POWER_POLICY_VIDEO_BRIGHTNESS__, 0, "UInt"), NumPut(0x4619B909, GUID_DEVICE_POWER_POLICY_VIDEO_BRIGHTNESS__, 4, "UInt")
,NumPut(0xD7F54999, GUID_DEVICE_POWER_POLICY_VIDEO_BRIGHTNESS__, 8, "UInt"), NumPut(0xCB0BAC1D, GUID_DEVICE_POWER_POLICY_VIDEO_BRIGHTNESS__, 12, "UInt")
}
return &GUID_DEVICE_POWER_POLICY_VIDEO_BRIGHTNESS__
}

_GUID_ACDC_POWER_SOURCE()
{
static GUID_ACDC_POWER_SOURCE_
if (!VarSetCapacity(GUID_ACDC_POWER_SOURCE_)) {
VarSetCapacity(GUID_ACDC_POWER_SOURCE_, 16)
,NumPut(0x5D3E9A59, GUID_ACDC_POWER_SOURCE_, 0, "UInt"), NumPut(0x4B00E9D5, GUID_ACDC_POWER_SOURCE_, 4, "UInt")
,NumPut(0x34FFBDA6, GUID_ACDC_POWER_SOURCE_, 8, "UInt"), NumPut(0x486551FF, GUID_ACDC_POWER_SOURCE_, 12, "UInt")
}
return &GUID_ACDC_POWER_SOURCE_
}

}

BrightnessSetter_new() {
return new BrightnessSetter()
}

At the very end of this, paste the following. This is the part of the script that you will modify to suit your own needs. The following changes the brightness via the Page Up and Page Down keys on your keyboard. It changes it by 10 i.e., when you tap the Page Up key once, the brightness goes up by ten levels.

Edit the levels to whatever you need. For example, you can change it to 1 and -1 to get finer control over the brightness.

BS := new BrightnessSetter()

PgUp::BS.SetBrightness(10)
PgDn::BS.SetBrightness(-10)

Save the script with the AHK file extension and run it. Use the keys you’ve set up to adjust brightness.

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