Intel HD3000/HD4000: Is there a way to enable dithering for external DisplayPort displays?

[PPave5]

6-bit displays demonstrate ugly banding when connected to DisplayPort. Dithering is enabled for eDP and LVDS displays, but I don't see how it can be turned on or off.

[idata]

Hello nitrocaster:

In regard to your question, the feature for dithering is actually included and enable on the graphics driver by default, so, there is no option on the Intel graphics control panel to enable it or disable it. Any questions, please let me know. Alberto

[PPave5]

It may be present, but like I said, dithering does not work for 6-bit displays connected to DisplayPort. It works for LVDS displays, though.

[idata]

Hello nitrocaster:

Thank you very much for that information. At this point, we will do further research in order to confirm that information, as soon as I get any details about that, I will post all the information on this thread. Any questions, please let me know. Alberto

[idata]

Hello nitrocaster:

I just wanted to let you know that I just received the results of our research, and actually, as you mentioned, we can confirm the dithering is automatically enabled in displays of 8bpc or higher and disabled for displays of 6bpc and lower, that is how this feature was designed. Any questions, please let me know. Alberto

[rx7jordan]

Hi sorry for replying to an old post but does this also apply to latest intel igpu and Intel arc GPUs? Thanks

[AlHill]

@rx7jordan    Old post?  Yes - 8-years-old.   Start a new thread with full information regarding your problem.

Doc (not an Intel employee or contractor)
[Maybe Windows 12 will be better]

[PPave5]

Why would someone decide that dithering should be disabled on 6-bit displays when it is actually required to hide banding artifacts? Limited color depth is the very case when dithering is used.

[idata]

Hello nitrocaster:

In regard to your inquiry, it was a design decision, there is a an specific department in charge of designing the processor, the specifications of it and how it works, they are also the ones that make the decision of which feature will be enable or disable for certain type of processors. Any questions, please let me know. Alberto

[PPave5]

So, Intel engineers intentionally chose to lower image quality and to not provide an option in graphics setup utility. Is there any good reason for this? There's no such problem in Ubuntu. Does that mean Intel forces users to migrate to Ubuntu?

[idata]

Hello nitrocaster:

In order to provide the information you are requesting, we will need to do further research on this matter, I do not want to give you false expectations, because I am not sure if we have any documents that will explain or have the information you need, but I will try my best to get them. As soon as I do that, I will post all the details on this thread. Let me apologize for any inconvenience. Any questions, please let me know. Alberto

[idata]

Hello nitrocaster:

I received some updates in the investigation we did on this matter, and I just wanted to let you know that our tests determined that If dithering is enabled, it impacts the test pattern accuracy as received by the receiver. So during early DisplayPort days it was decided to keep it disabled for external DP as 6bpc external DP displays were literally not present. Nowadays, the vast majority of displays are minimum of 8bpc (24bpp), and this is only going to increase in the future. Regards Alberto