Elitebook 8560w Dreamcolor: brightness flickering in dark scenes

I have one issue with my 8560w's DC screen that I haven't seen mentioned anywhere, I hope someone with DC display can check this. Sometimes in darker scenes in videos, when there is a lot of gray/black/dim colors on the screen, I can see brightness flickering, like it does adaptive brightness/contrast adjustment on the monitor. It's not random, and doesn't seem like a malfunction. I don't have any software installed that would do this, nor any settings set for this in player/decoder software, and all the relevantly named settings in Nvidia control panel are turned off. Even more, I checked this on linux livecds with vesa video driver: I set desktop theme and background to the one with gray colors, and moved windows with white background around (it was drawing them while moving, not just dragging window borders) - and I got this effect again.

So I can only assume that Dreamcolor does this on purpose for some dark/dim scenes, like this a function in its firmware. It's not just my eyes or in my head for sure, because other people I asked to look at this also noticed this change in brightness. You'll have to be looking for it specifically.

Can anyone with DC please check if they have this effect? It looks kinda like dynamic brightness/contrast which can be found on some consumer desktop monitors. Should be noticeable in dark video scenes (some night/low light scenes in movies, for example), or if you set Windows Aero theme to black interface color, wallpaper to some dark gray image, and move some windows with white backgrounds around. I can sometimes even see it when I'm just scrolling some webpages in my browser, like HP's own US store page (it has dark background).

Apart from this sometimes very annoying brightness flickering, I don't have any problems with DC that were mentioned in other threads, like green tint, no factory calibration, etc.

 

Hi Tex,

i have read this thread a few days ago, and i have not had this symptom, until i upgraded the graphics driver for the amd firepro m5950 to version 8.911.3.1.

After the driver update i too experienced the brightness flickering. First i thought it might be connected to the ambientlight sensor, but i did disable that when i got the notebook a few months back.

I think i just found the culprit for the brightness flickering. In the Catalyst Control Center there is an option called Vari-Bright. I think it was enabled as soon as i installed the driver. After disabeling this feature ( bug ? ) everyting is back to normal. The brightness flickering is gone.

If you also have a Firepro m5950 you should check if the vari-bright option is responsible for the brightness flickering of your dreamcolor panel.

edit //

i have just reread your post, and i guess i might have missed the part with the nvidia control panel. Well in this case that Vari-Bright is not responsible for the flickering of your screen it may very well be the ambient light sensor that is responsible for the flickering.

In this case it is definitely worth looking in the bios ( uefi) if the ambient light sensor is activated. The sensor reads the "ambient" brightness. So my guess is that if it is activated and the screen is bright the sensor picks up some of the light from the display panel itself and it dims the display. Once you have those gray/black/dim colors on the screen the display does not radiate very much light , and thus the sensor is switching the brightness levels up and down.

 

Hi, schoko. Thanks for replying.

Yes, I forgot to mention that I have Nvidia Quadro 2000m, and that I disabled ambient light sensor in BIOS ever since I bought me 8560w. This flickering is still noticeable even if ambient sensor is enabled in BIOS and active under Win7.

Here are more details about my config: I made a clean install of Win7 and didn't install any HP software, only basic drivers for 8560w from HP's site, and quadro drivers from Nvidia's site. Since it is reproducible in Opensuse livecd with basic video driver, it doesn't look like it depends on the video driver. Changing BIOS settings available under F10 during boot doesn't change this dynamic brightness situation.

I should note that I have HP ZR24w monitor and Acer monitor connected to the my 8560w through dock station's DisplayPort and D-Sub, and they don't have this symptom (checked on the same video in monitor cloning setup, and individually).

This flickering only happens on Dreamcolor when image on the screen changes in certain way.

 

Hi,

I have the same problem, but with HP 8770w DreamColor with quadro k4000m. The display flickers (whites) with some tones of gray/black. It also flickers when accessing Win8 right hand side panel.

The flickering is visible when playing video content : but it is present constantly on the same part of the video (the flickering is not visible on external monitor with duplicate display or any other computer), it is also visible for example in Photoshop when adjusting curves to image, when you reach certain point of gray/black shadows/colors.

I have taken the laptop to service, they changed motherboard, lcd panel, graphic card and the problem is still present.

Before that I tested with different drivers (official and 3rd party), different OS and the problem persists.

If anyone has any news or solutions I would be more than happy.

Thx

p.s.

does any of you with DreamColor panels notice buzzing noise from top right hand side of the panel. It stops if lcd panel is on standby (not active) and it changes in intensity if you change brightnes. Anyeone?