Author: Adam Simmons
Last updated: November 7th 2020

From the system tray, launch the Nvidia control panel. Next, go to Display adjust desktop color settings. From there, select the display and then select the Nvidia Settings. After that, change the options accordingly in order to get the correct combination though you can always leave them to default. Adjust desktop color settings Nvidia The following settings in the NVIDIA Control Panel also will fix the color problems. 3D Settings Adjust image settings with preview. Check the option – Use my preference emphasizing: Quality.

Pretext

This article provides guidance for users with discrete desktop GPUs from Nvidia and AMD. For mobile GPUs or integrated graphics solutions, including those from Intel, it is recommended that a custom resolution is set using CRU (Custom Resolution Utility). Refer to the Nvidia section on this, specifically the second half of “Second solution: setting a custom resolution” where the process of using CRU is mentioned. Users with Intel graphics chipsets should alternatively look for an option called ‘Quantization Range‘ in the Intel Graphics Control Panel and ensure it is set to ‘Full Range’.

Introduction

You may have heard people say that the image quality of HDMI (High-Definition Multimedia Interface), DP (Display Port) and the now outdated DVI (Digital Visual Interface) are equivalent. They’re digital signals that either ‘work’ so the monitor displays an image or ‘don’t work’ so that it doesn’t. A user just has to consider the bandwidth requirements of their monitor and choose a port on the GPU (Graphics Processing Unit) and monitor that will support the full resolution and refresh rate of their display.

Unfortunately things aren’t quite as clear-cut as that, and there is a murky middle ground. It’s this quagmire in the middle that many users will find themselves stuck in due to how HDMI is typically handled by PC graphics cards. HDMI is designed as a universal signal widely used by TVs and entertainment systems, unlike DVI and DisplayPort which are built from the ground up as computer monitor ports. The aim of this article is not to bog you down with all of the technical fripperies of these different ports and associated aspects. Rather it’s designed to give you some straightforward actionable advice which will allow you to optimise the HDMI colour signal for PC use.

How Nvidia GPUs handle the HDMI signal

The problem

Whenever a monitor with a resolution and refresh rate in common with HDTVs (e.g. 1920 x 1080 @60Hz) is connected to an Nvidia GPU by HDMI or DVI-HDMI cable, the GPU tends to treat the screen as an ‘HDTV’ rather than a monitor. You can see how the graphics driver categorises things for the Full HD resolution as that shared with a TV by opening the Nvidia Control Panel and navigating to ‘Display’ – ‘Change resolution’. It will usually be listed under ‘Ultra HD, HD, SD’ as ‘1080p, 1920 x 1080 (native)’ as shown below.

Although this behaviour is typical for 60Hz 1920 x 1080 (Full HD/1080p) displays connected by HDMI it occasionally applies to such displays connected by DisplayPort as well. In the image above you may notice that a Dell U2414H, connected via DisplayPort, has been categorised in this way. This is rather bizarre behaviour considering DisplayPort is a PC-only connection not currently employed by TV screens. If you connect a monitor up using DVI or a DisplayPort connection that works as it should then the resolution will be listed in a separate list entitled ‘PC’ as shown in the image below.

But the problem is not simply that the resolution is put on the wrong list, it’s the effect that this has on the colour signal that is important. With the HDMI (or incorrect DisplayPort) connection the GPU sends out a ‘Limited Range RGB 16-235’ colour signal rather than the ‘Full Range RGB 0-255’ signal the monitor is designed to process and indeed sends out via DVI or correctly functioning DisplayPort. Without going into the intricacies of how these colour signals differ, there is a definite mismatch between the colour signal sent to the monitor and the screens native capabilities. This disparity leaves the monitor unable to display shades with an appropriate depth and variety. Black appears an obvious dark grey (overall static contrast suffers – this is measurable) and the gamma curve is shifted such that many shades appear a lot lighter than they should. The whole image looks like it has a sort of bleached haze over it, giving what is commonly referred to as a ‘washed out look’. Confusingly, we’ve also observed the GPU defaulting to the ‘Limited Range RGB 16-235’ signal when connected to ‘4K’ UHD (3840 x 2160) screens – even though the resolution is listed under ‘PC’ as ‘3840 x 2160 (Native)’.

The table below gives some basic readings taken from the AOC i2473Pwy connected by HDMI and set to use both a ‘Limited Range RGB 16-235’ signal and a ‘Full Range RGB 0-255’ signal. Results for a third signal type discussed below, ‘YCbCr444’, are also included. The ‘Test Settings’ and equipment from the review were used to take these readings – a Spyder4Elite for the gamma and white point measurement and a Konica Minolta CS-200 for the rest. The ‘Test Settings’ simply involved lowering the brightness a bit and making minor colour channel adjustments.

Nvidia solutions

First solution: functionality now built into the Nvidia display driver

As of driver version 347.09, Nvidia have added a small drop-down to the Nvidia Control Panel (NCP) that will allow you to enforce the correct ‘Full Range’ signal. Simply open NCP and navigate to ‘Display – Change resolution’. You should see a drop down box labelled ‘Output dynamic range’. At time of writing this is the final drop-down box on the page, under ‘Apply the following settings’ as shown below.

Make sure this is set to ‘Full’ rather than ‘Limited’ and press ‘Apply’ to enforce the ‘Full Range RGB 0-255’ signal. ‘Limited’ is used by default on Full HD monitors connected using HDMI and some connected using DisplayPort, when running at 60Hz or other refresh rates listed as ‘Ultra HD, HD, SD’. For resolutions or refresh rates listed as ‘PC’ the default setting will be ‘Full’. If the monitor has an ‘HDMI Black Level’, ‘HDMI RGB PC Range’ or similar option make sure this is set to ‘Normal’, ‘High’, ‘Full’ or ‘RGB (0~255)’ rather than ‘Low’, ‘Limited’ or ‘RGB (16~235). The exact nomenclature depends on the monitor model.

Second solution: setting a custom resolution

It is possible to enforce a ‘Full Range RGB 0-255’ signal over HDMI or incorrectly functioning DisplayPort by setting a custom resolution. This resolution can be set such that it is treated exactly the same as the default native resolution of the monitor but with the colour signal corrected. The video below shows this process, focusing on 60Hz where the issue is most likely to occur. Again ensure that the ‘HDMI Black Level’ or similar option on the monitor is set correctly, if such an option exists.

After creating it, you can see your new ‘Custom Resolution’ listed separately in the Nvidia Control Panel resolution list as shown below.

Although this will work with most applications and the desktop, some games ignore custom resolutions and will revert to using your monitor’s native resolution with the default colour signal. On many such games your custom resolution will be used if you set the refresh rate to a value other 60Hz (essentially overclocking or underclocking your monitor if it’s a 60Hz model). Most 60Hz Full HD monitors will be able to use 65Hz without any issues, some can be pushed further if you’re feeling adventurous. Some users would be uncomfortable changing this from the default 60Hz, which we understand, so for those looking for a simple ‘universal’ fix there are some alternatives.

One alternative to setting a custom resolution in the Nvidia Control Panel is to use the ‘Custom Resolution Utility (CRU)’ created by ‘ToastyX’. Full instructions on how to use this are included in the first post on the thread linked to. Simply run this util

Default Nvidia Desktop Color Settings