2 Replies Latest reply on Dec 7, 2015 3:11 PM by JohnRoss2113

    (HD Graphics 4000) I need to disable hardware-based Content Adaptive Brightness Control (CABC) but have no option


      Hi all,


      I want to install a new LCD panel in my Intel Core i7/HD4000-based laptop. The intended replacement is a glossy HannStar HSD173PUW1-A - to replace its original very grainy Chi Mei 173HGE. However, I have encountered a problem, not documented anywhere except its datasheet, that the HannStar has hardware-based Content Adaptive Brightness Control (CABC). This means that right from the point of booting in the BIOS, it attempts to 'intelligently' decrease the backlight as the proportion of dark pixels on the screen increases.


      Suffice it to say that I cannot stand this, for reasons of both (A) distraction as whites alter in intensity of their own accord and (B) reduced quality as colours lose saturation on 'darker' screens. I have had to revert to the original super-grainy Chi Mei simply because the grain is LESS annoying than the CABC in the HannStar: grainy whites are marginally better than whites that cycle in brightness whenever I open a dark website or a Command Prompt. :/


      Let's save ourselves a lot of repetition: I have tried all the usual things recommended in all the threads found by Google. These included disabling all brightness-related settings in the Intel control panel and Windows itself, uninstalling my OEM HD4000 drivers and reinstalling the latest versions, etc. - to no avail. There is no option for Automatic* Brightness in Intel Graphics, my BIOS, or anywhere else. Disabling the usually recommended things like Power Management in Intel and Windows had no effect; the auto-brightness is system-wide and occurs even in my (near-useless) OEM BIOS. This indicates it's set on the hardware level.


      Indeed, having delved into the spec/datasheet - attached - for the HannStar, its CABC is enabled by a single pin on the 40-pin LVDS connector being set to low voltage/0 and disabled by high voltage/1 (this seems backwards to me, but what can ya do). Thus, I assume that to disable it, I would have to instruct the HD4000, on a system-wide level, to set this pin to high voltage. Perhaps this is what the "Automatic Brightness" in the Windows app (*edit: not Adaptive, as this is not related to ambient light levels at all) would do, but I have no such option! Therefore, I would need an Intel control panel app with the option not hidden from me - as presumably it does not detect CABC's presence - OR a way to modify this on a BIOS level.


      I hope this is a feature that can be delivered. And I appreciate all comments from fellow users - as long as they're not simply asking me whether I have read the countless threads I've already read or toggling the countless options I've already toggled! ; ) Thanks in advance to all for constructive replies.

        • 1. Re: (HD Graphics 4000) I need to disable hardware-based Content Adaptive Brightness Control (CABC) but have no option

          Hi db0451,


          I am sorry to hear you are having problems but let me help you with your query.


          Based on the information you have provided and the research from my side, the feature in mentioned is a feature that comes with the Screens, either monitors, TVs, etc… but it is not handled by the Graphics controller meaning that there is no option in the Graphics & Media Control Panel to turn off this technology.


          My best recommendations is to contact the screen manufacture and confirm with them if the feature can be disabled or contacting the computer manufacture to confirm with them if the BIOS contains an option for this technology.

          • 2. Re: (HD Graphics 4000) I need to disable hardware-based Content Adaptive Brightness Control (CABC) but have no option

            Intel HD Graphics 4000 and Windows 10 & Windows 8.1   ( Brightness fix with latest driver)




            Brightness Fix with Driver Date 8/17/2015 )




            Brightness problem Solved


            Intel HD Graphics 4000 with NVIDIA® GeForce® GT650M graphics.




            Intel HD Graphics 4000 Driver,     Driver Date: 8/17/2015


            Driver Version:


            Make sure you backup your registry first before proceeding!!!!


            open regedit  in  Run Command


            Registry has wrong value:


            Currently reads as :


            [HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Control\Class\{4d36e968-e325-11ce-bfc1-08002be10318}\0000] "FeatureTestControl"=


                                                                                      "Edit DWORD 32 bit"=       f000


            Registry with New Value:


            You needed to change the value in registry to:  (   f008   )


            [HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Control\Class\{4d36e968-e325-11ce-bfc1-08002be10318}\0000] "FeatureTestControl"=


                                                                                     "Edit DWORD 32 bit"=        f008


            Then Restart Computer


            Brightness Fixed with Latest driver.


            Let me know if this was helpful to you