How can I improve my laptop screen's video quality with dark scenes (color banding)?

Question

I have an HP ZBook G2 laptop with a DreamColor screen, Nvidia Quadro K5100M graphics adapter, and Windows 10. When I bought the laptop in 2016, it offered multiple choices for screens and graphics adapters, and the DreamColor and Nvidia Quadro K5100M options were by far the most expensive options, so I thought I'd be getting the best image/video quality out of it.

But I have always noticed terrible video quality on this laptop when watching videos with dark scenes. The quality is a lot worse than an older ThinkPad T60 laptop from 2006 with Windows XP.

Here is an example showing the exact same video file on both laptops, playing in VLC media player, paused at the same place (these are photos of the laptops' screens, not screenshots). The newer HP ZBook laptop looks like:

The older ThinkPad laptop looks like:

I also took this photo of the HP ZBook laptop duplicating its screen (on the left) to an external monitor (on the right):

As you can see, the gradations on both the older ThinkPad laptop and the external monitor look very smooth, while they look very rough/pixelated on the newer HP ZBook laptop. Apparently this phenomenon is known as "color banding".

Since the HP ZBook laptop's output to an external monitor looks fine, that would indicate the problem is related to the ZBook's DreamColor screen and not its Nvidia K5100M GPU.

It is extremely disappointing that the HP ZBook's DreamColor screen, which was supposedly the best laptop screen one could buy at that time, looks so much worse than the ThinkPad screen, which is almost 10 years older. Are there any settings I can change in Windows 10 or the Nvidia Control Panel to have the HP ZBook's video quality be more like the ThinkPad and external monitor?

I did see a setting in the Nvidia Control Panel for the "Output color depth", although I'm not sure if that would have any impact on this problem. Currently it is set to "8 bpc", and it shows a "10 bpc" option:

Unfortunately, when I change it to "10 bpc" and click "Apply", it automatically changes back to "8 bpc". I'm not sure why it won't let me change it to "10 bpc". Everything I have read about the DreamColor screen and Nvidia K5100M tell me that they both support 10-bit color. But I don't know if the ThinkPad with Windows XP supports 10-bit color - if it doesn't, then changing the ZBook to 10-bit probably won't help.

Additional information: I just tried booting up the laptop using a SliTaz Linux Live DVD to see if the problem also happens in a different operating system. I played the exact same video file, and although it is still pixelated in dark scenes, it definitely isn't as bad as it is in Windows.

Answer 1

You may color-calibrate your new monitor to your color preferences. For a laptop, the success of the below method may depend on the color adjustments possible for your model, or on utilities supplied by the manufacturer (you should also look for display software available for download on the manufacturer's website).

• Run Settings > Display and set your resolution to the recommended one
• Enter in the Start menu calibrate and click "Change advanced colour management settings for displays, scanne..."
• In the "Colour Management" display, go to the "Advanced" tab
• Click "Calibrate display"
• In the dialog that spans your whole screen, click "Next" twice and start the calibration process
• You will be able to adjust the display settings of gamma, brightness, contrast and color balance, for both Windows and the monitor (if your laptop monitor can calibrate these settings)
• And the end you will be able to compare the new and old settings and click "Finish" to apply the settings or "Cancel" to discard the new configuration.

For more details with screenshots see the article How to calibrate your PC's monitor on Windows 10.

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As the above didn't work for the poster, I have done further research and found an interesting Linux driver patch that mentions that the builtin eDP panel in the HP zBook 17 G2 returns bad EDID info for the screen's depth, so drivers will fall back to a lower bpc setting.

The Linux driver patch basically overrode the missing data using the screen's unique identifier, so is able to use the screen with a better quality.

Such a fix was evidently only done in Linux, while the Windows driver is still unable to use the screen at its best quality of 10 bpc.

You may signal the problem to NVIDIA Support, but I don't believe that there will be any speedy solution to the problem.

Answer 2

I found the solution! According to a forum post:

As others may have pointed out, on the Dreamcolor display, by default, 10bpc color depth is not selected in the NVIDIA Control Panel. This causes severe color banding on the display, and it looks worse depending on what you're doing. On the latest NVIDIA drivers supplied by HP, if you try and select 10bpc in the control panel, the screen will flicker black, and then it will revert back to 8bpc again, making it impossible to even select 10bpc. Now, if you revert back to driver version 385.73 ( which Windows will also install by default at first system launch if you don't update any drivers via HP's website ), you can get your GPU to output 10bpc

So I installed version 391.33 of the Nvidia driver (since I couldn't find version 385.73), and I was finally able to change the "Output color depth" in the Nvidia Control Panel from 8 bpc to 10 bpc. Dark video and images look so much better now!

Not sure why the recent versions of the Nvidia driver don't allow you to increase the color depth to 10 bpc, but I'm glad the older versions are still available.