How to Calibrate Dell Wide Gamut Monitors

Guest Poster

In the past, hardware calibration feature was limited to premium wide-gamut models from companies like NEC or Eizo. Those models offer wide gamut, great uniformity and advanced calibration features…but at a fairly high price. Affordable wide gamut solutions with hardware calibration started in 2013 with Dell and after that other companies like LG, BenQ and Samsung begun to offer “similar” products with more or less success. It is important to point out that LG and Samsung wide gamut models cannot be properly calibrated internally with the i1Display Pro colorimeter using their software and the same applies to some BenQ models like SW2700PT and its Palette Master Elements software. The main issue with those models is that they bundle an outdated X-Rite SDK (Software Development Kit) in their software without GB-LED support, which is the current main* (see the footnote at the end of the article below) LED wide gamut backlight technology. Hence, their software won’t get the same accurate readings as with the proper correction, which in turn leads to less accurate calibration than it should. The BenQ PG2401PT and its Palette Master software, on the other hand, come with proper GB-LED support.

Updated on 06/06/2018: X-Rite / Dell released a new version of DUCCS software 1.6.5 – please see the notes below. All current Dell Wide Gamut monitor owners are highly encouraged to update and recalibrate their screens to get better accuracy.

These low-budget wide gamut monitors were an interesting option for hobbyists and professionals, who cannot or do not want to spend more than $1,500 on a fully-featured premium wide gamut monitor from NEC or Eizo. The release of Eizo CS240 in late 2014 lowered that budget gap, since it is a near fully-featured wide gamut monitor for $850-900 USD and was one of the most sensible and affordable choices.

Since 2013 Dell has released several GB-LED models with hardware calibration. Here is a brief overview of their features:

And below are their issues:

This is the sad tale of affordable wide gamut monitors, a promise that could be, but wasn’t. Some of them truly offer value for their price and still can be purchased today if they are sold for a fair price: U2413, U2713H or UP2414Q…and even UP2516D / UP2716D but it’s highly recommended to check color uniformity (ArgyllCMS/DisplayCAL).

When looking at its competitors in its price range, the sad tale becomes a tragedy:

Given these facts, I would stay away from any of these Dell models with high prices since they are not worth it: the risk of bad uniformity units is too high for the bigger screens and software for hardware calibration has some issues as we will see in this article. I would stay further away from LG or BenQ models since their cheap models have worse uniformity issues than Dells (at least worse than 2013 models) and their software is unable to measure them properly with a colorimeter. Crippled contrast after you enable uniformity compensation in Samsung’s 32” 4K wide gamut is not appealing for such an expensive monitor…you can get a fully featured 27” QHD wide gamut from NEC for that price and NEC offers 5-step uniformity compensation trade-off between max contrast and max uniformity.

This does not mean there is no hope for hobbyists or professionals with limited budgets. As I have pointed out before, models like U2413, U2713H or UP2414Q seem to be a sensible choice… but only if found for a fair (I mean low) price for their value, since they are pretty old models. Customers need to be aware of these Dell limitations before buying. This is the point of this article: to learn, evaluate and if possible fix their flaws.

Eizo CS240 (24” 1920×1200, like U2413) had an affordable price too and it’s very likely that it will show better color uniformity than Dell. It offers true uniformity compensation feature but it’s only an ON/OFF feature, there is no tradeoff for contrast-uniformity. Its price is about the price of a 27” QHD GB-LED Dell like UP2716D, so this Eizo is another sensible choice for limited budgets.

For better uniformity or more calibration and color space emulation features, save money for middle-high (Multisync PA) or high end (Spectraview PA) GB-LED models from NEC since they are cheaper than Eizo counterparts. NEC’s Spectraview PAs offer the same quality as ColorEdge CG Eizos and the cheaper Multisync PA models offer better features than Eizo CX series.

Dell Color Calibration Solution (DUCCS)

After GB-LED family presentation, let’s see what these Dell owners can get out of their monitors and DUCCS software. Since v1.0.x versions were useless, this is a guide to the 1.5.x and 1.6.x family:

-1.5.3 which works with 2014 generation or older models. This is the recommended version for that monitors unless you notice bugs.
-1.6.5 is the latest version that is needed for the most current Dell monitor models.

Quick notes on the latest 1.6.5 release:

This update seems to work with all DUCCS compatible monitors including old models like U2413, U2713H… etc. on Windows 10. You should update DUCCS to this new version. I’ve seen no USB communication errors or crashes but if you find issues report them to Dell/X-rite.

As a side note, with DUCCS 1.6.5 comes an update to X-rite Services. That update carries a new EDR spectral correction called “Panasonic VVX17P051J00 in Lenovo P70” with a gamut close to but smaller than P3. This spectral correction is not intended to be used with current photo wide gamut monitors. Spectral power distribution (SPD) of this backlight once plotted in a 2D graph is close to SPD from a new “P3 iMac” but its gamut is just a little bit smaller than those iMacs which are almost full P3. It is also smaller (by a huge amount, like iMacs) than the gamut of newer Dell UPs or newer CG Eizos like CG247x, CG2420, CG2730. I would like that X-rite include a spectral correction for these new wide gamuts (usually called “W-LED” backlight where W is not like WLED -white led- backlight of sRGB LED displays). They have it, at least one sample called “HP_DreamColor_Z24x_NewPanel”, but they offer it just to HP hardware calibration software. You can import that HP spectral correction manually (go to HP website) if you want to measure an UP2716D with DisplayCAL or make a graphic card LUT calibration with DisplayCAL in these Dell’s “Custom Color” OSD mode… but you cannot use it in i1Profiler or DUCCS (limited to GB-LED, called “RG Phosphor” in X-rite’s naming). X-rite tools available to their customers need an update regarding this subject: more EDRs (spectral corrections) for current backlights.

User interface and almost every option are common to all 1.5.x and 1.6.x versions, so unless stated otherwise this guide works with all of them. The following instructions are for the Windows version of DUCCS, OSX version should behave in a similar way unless bugs or Apple hardware limitations or incompatibilities are found. Ask Apple support team if DUCCS does not work for you…you are on your own since it seems that there is no official support of Dell monitors with Apple proprietary hardware configurations.

DUCCS included on your monitor driver CD may be outdated. They can be downloaded from Dell or Xrite websites. Below are the links to Windows versions (Windows 7 or newer is required):
DUCCS 1.5.3 (don’t worry about the model name on the page, it works with all 2014 and older models):
DUCCS 1.6.5 (the latest version)

Installation will need administration privileges; it will also install i1Display Pro SDK, X-rite Services and .NET Runtime. After installation, which may require a reboot, you may want to check Windows Update for .NET Runtime security updates. Al the end of the process you should have a desktop shortcut to DUCCS. Before running DUCCS, plug in the i1Display Pro colorimeter. Windows may want to install is as a HID device (like a mouse, keyboard…), let it do the job.

The newer 2016 Dell UltraSharp models may need a firmware update (at your own risk).

While newer versions of DUCCS may work with a dual monitor setup, it is strongly recommended that there is only one widegamut LED Dell connected to your computer when running DUCCS (or even one monitor at all). Calibrate each display separately.

Now run DUCCS. If you are running 1.5.3 and have Internet access, it will prompt you to update to 1.6.5. This new version is worth trying for the new features and bug fixes. After it starts you should see DUCCS main screen which looks like X-Rite’s i1Profiler for those familiar with the program:

On the middle of the screen you will see a “User Mode” selection. Go ahead and pick the “Advanced” option so that you can see all the available calibration options.

Next, click “Display -> Profiling” to proceed with internal Calibration. The next screen will show your Dell monitor with its serial number and a set of presets for calibration target. If you do not see this screen and you see the usual i1Profiler calibration target with white point, luminance and contrast, then your monitor is not recognized by DUCCS as a Dell with hardware calibration. Unfortunately, it is a common issue for 2013 Dells under OSX. Here is how the screen should look like:

A brief explanation of the presets:

You may have noticed that “sRGB” and “AdobeRGB” presets are just particular configurations of “Custom xy” and it’s true. You only need to know CIE xy color coordinates for R, G and B of sRGB and AdobeRGB (available on Wikipedia for example) in order to manually set an AdobeRGB calibration target without presets.
It is very useful if you want to calibrate to sRGB/Rec709 gamut, D65 white but 2.35 or 2.4 gamma for video purposes: just go to Wikipedia, get xy coordinates and setup your desired white and gamma.

DCCS does not allow custom contrast value, it will aim to the best contrast that fit its needs. If you need a fixed contrast value (paper) you cannot do it with DCCS, you will need GPU LUT calibration and tweak monitor’s brightness and contrast controls under “Custom Color” OSD mode.

After choosing your calibration target, click next. Now you are prompted to choose a profile configuration, the way monitor behavior will be stored in an ICC/ICM file after calibration:

Here is a short explanation of the options:

After choosing profiling options, click next.

Now you are prompted to choose a number of color patches for profiling. These patches are not for calibration, just to profile your monitor. With DUCCS you cannot choose patch set for calibration and this is one of the former main reasons of its inaccuracy. The bigger the patch set, the more information DUCCS can use to compute display’s profile in an accurate way. The simple nature of matrix profiles makes them suitable for a low number of color patches.

Click next.

Now you must choose where to store calibration: Calibration 1 (CAL1) or Calibration 2 (CAL2):

If this screen does not show up, you are not able to hardware-calibrate your Dell because of some software or hardware issue. If an error shows with information about “no USB cable plugged from monitor to computer”, check it, but maybe monitor’s USB hub drivers are not properly installed, or maybe it’s a DUCCS bug. Sadly, if this happens, you are on your own. You can report this problem to Dell or X-rite.

At this DUCCS step, the software tries to communicate with your monitor in two ways (DDC/CI and USB) to read the serial number. If any of these operations fail, this kind of error happens.

If there are no errors, proceed by clicking “Start Measurement”.

At this point of calibration, DUCCS will go fullscreen and will prompt you to uncover the i1Display Pro lens and place the device on the center of screen. When done, click next.

Now, the actual calibration starts. User has no control during this process so just sit and wait:

At this point CAL1 or CAL2 are calibrated to our desired target, but you need an ICC profile too because color managed applications need to now actual monitor behavior to manage color properly. DUCCS starts a series of patch measurements (chosen in profile configuration step) and stores that information in computer’s memory.

After all patch measurements are finished, DUCCS will ask you to place close the i1Display Pro lens. Click next after you are done. Then DUCCS goes back to windowed mode. Click next.

Now you are prompted to choose a profile name. Write a meaningful name like “DELL U2413 sRGB CAL1.icm”, do not overwrite the generic “U2413.icm” profile. Click on “Create and save profile”, which will transform profiling measurements to a profile and write it to an ICM file, stored in your Windows OS profile folder. It will also set it as a “Default Profile” for your Display in the “Color Management” configuration of Windows Control Panel. That means that all color managed applications will work like if that profile accurately describes your monitor, but this won’t be true if you either factory-reset the monitor / reset that CAL1/CAL2 slot or change OSD mode from your CAL1/CAL2 to other mode.

Now you can repeat the process for the other CAL1/CAL2 slot or exit DUCCS since all other application options are not useful: uniformity, validation…not as reliable as DisplayCAL, not so accurate so not to be trusted. We will deal with validation and uniformity measures in next article.

Since calibration is stored inside the monitor, you can take DUCCS’ ICM files with its behavior to another computer or OS (Linux, OSX, another computer with Windows), then install one of those profiles as the default profile for your display. Profiles are stored in “C:\WINDOWS\system32\spool\drivers\color” folder in Windows OS.

You need to know that OSD brightness/contrast values for CAL1 and CAL2 are independent from the other OSD modes, but they may be independent too for each DVI/DP/HDMI input (may vary with model/firmware revision). If you calibrate your Dell monitor on a desktop computer connected with a DVI cable to your monitor and you want to use that calibration with a laptop connected with HDMI to your monitor, then you may need to copy OSD contrast & brightness value from CAL1/CAL2 modes in DVI input to CAL1/CAL2 brightness and contrast controls in HDMI input. CAL1 and CAL2 computed LUT will remain unchanged between monitor inputs, it’s just contrast and brightness values what you may need to copy to the other inputs. The same applies to RGB gain and offset controls for “Custom color” OSD mode (for GPU calibration), each DVI/HDMI/DP input may need its own configuration.

Color Management Configuration for MS Windows

If you go to Windows Control panel, and double click on “Color Management” you can change default profiles for each of your displays. On Windows 10, visit “System”, click “Advanced Display Settings” under “Display”, then click “Display adapter properties” under “Related settings”. When a new window comes up, click on the “Color Management” tab, then “Color Management…” button to see the following screen:

Under the “Devices” tab there is a Device drop-down box. Make sure that your Dell display is selected. Don’t forget to check “Use my settings for this device”. Below that you will find a list of profiles associated to that display. You can add and remove profiles. You must select as “default” profile the profile that matches your current monitor configuration before using color-managed applications. For example, for CAL2 calibrated to AdobeRGB preset in a U2413 with DUCCS, there must be a profile with your desired name, “DELL U2413 AdobeRGB CAL2” ICM file. Make sure that this profile is set to “default” while in CAL2 OSD mode.

Do not change anything in the “Advanced options” tab – leave it as is. The only change that may make sense for some configurations is to enable Windows LUT loader for GPU but it is not recommended. To enable it, click on the bottom button “Change system defaults” (administrator rights are needed). It will open another “Color management” configuration. Go to advanced tab and enable “Use Windows display calibration”. Then close all Color management windows.

With this LUT loader enabled, every time you set as “default” a display profile, Windows will load that profile’s calibration curves in graphics card LUT. DUCCS profiles have a linear LUT (no calibration), so this configuration is not needed, but if you use i1Profiler or ArgyllCMS profiles mixed with DUCCS ones, then it may be useful. Windows LUT loader is less accurate than ArgyllCMS LUT loader. It will load a low-resolution version of calibration curves (without “decimal values” we talk about in my Basics of Monitor Calibration article) which may lead to banding artifacts. This does not matter at all for DUCCS profiles, they have a linear LUT calibration embedded. Unless for some strange reason you do not want to use 3rd party LUT loaders, I would avoid MS Windows LUT loader and use ArgyllCMS/DisplayCAL. DisplayCAL 3.3.x comes with an autoloader that notices a change in “default profile” (actually it seems to be a polling mechanism) for each display in your OS, and IMHO it’s the way to go.

Keep in mind that if you change the preset mode on the monitor to a different one (say from sRGB to AdobeRGB) and forget to change it in the Color management settings above, then fire up Photoshop, all colors might be wrong. Your display (while in that OSD mode) has a close to AdobeRGB behavior, but Photoshop will do color management as if it was close to sRGB. Before you open a color-managed application, there must be an accurate profile for your current OSD mode set as “default” for your display, as shown above. This is not a Dell limitation, this is true for every monitor and every operating system… unless a color managed application has its own monitor profile configuration. Because of this, always make sure to select the same preset (CAL1 or CAL2) as the default Color Management profile in your settings. If you change one, don’t forget to change the other. It may be possible to do this change sequence automatically with a third-party application like Dell Display Manager (after tweaking it, out of scope of this guide). The same happens with Eizo/NEC monitors and their OSD configuration programs.

*NOTE: X-rite packed a GB-LED backlight SPD sample under “RG_Phosphor” EDR file – it covers AdobeRGB 99% LED backlight models. That GB-LED SPD is not exactly the same LED backlight for iMac 5K DCI-P3 (smaller gamut) or super high-end Eizo CG318-4k (bigger gamut); there is a noticeable difference in red channel output SPD between GB-LED backlight and those two models. ArgyllCMS with SPD sample data from those two displays (a “CCSS” file with SPD data) can properly measure those displays with an i1Display Pro, so do not worry about it.

Validating DUCCS results

As seen on the previous page, DUCCS could make some mistakes or take some assumptions like that monitor has a nearly ideal uncalibrated behavior when measuring and computing LUT calibrations for Dell monitors. This means that your calibration may be not be as good as it should be, which is the reason you might want to validate it. The built-in DUCCS validation feature is not accurate either and it has no means to correct some issues even if its validation was useful.

For much more reliable and accurate validation of calibration results from DUCCS, you will need a third-party application called ArgyllCMS, which is free software under GNU license, available for all major OS platforms including Windows, Linux and OSX. This method of calibration validation using ArgyllCMS is not exclusive to Dell monitors, so you can also use it to validate NEC, Eizo or other monitors. ArgyllCMS is developed by the talented Graeme Gill and while it is completely free, if you like the tool, you can always support its development with PayPal contributions.

ArgyllCMS can calibrate (GPU LUT, in graphics card LUT) and profile your monitor, but also profile printers and scanners or even compute LUT3D data to use with compatible software for video. In order to install it, you only need to download the zipped executable for your platform and decompress it in a folder. No installation is needed. There are only two requirements:

ArgyllCMS is a set of command line applications that are definitely not user-friendly, since a set of long command line orders and parameters must be typed in your OS console. To solve this issue, it is ideal that you use a proper Graphical User Interface (GUI) for ArgyllCMS. One such tool related to monitor calibration and profiling is DisplayCAL (formerly known as DispcalGUI) developed by Florian Hötch. Just like ArgyllCMS, DisplayCAL is also completely free, the development of which you can also support via PayPal donations.

There was a major change in UI between 2.x and 3.x version, the latter being more like i1Profiler. Also 2.x versions feature an auto LUT loader on startup from profile. That feature was dropped in the first versions of 3.0 (bad) and later moved to DisplayCAL taskbar autoloader, which automatically loads ICM calibration for GPU LUTs in OS configuration (excellent feature). In this article, we will cover the installation and use of ArgyllCMS and DisplayCAL 3.3.1 for Windows, with i1Display Pro colorimeter. It is recommended to get the latest version.

ArgyllCMS and DisplayCAL have lots of options, so this is just a simple guide to cover a general validation mechanism and some particular issues related to Dell monitors.

ArgyllCMS and DisplayCAL Installation

The easiest way to install ArgyllCMS and DisplayCAL is by first downloading DisplayCAL and running its installer. Head on over to DisplayCAL’s website, navigate down to “Get DisplayCAL standalone”, choose your operating system and start the download process for the latest version. I downloaded the version for my Windows 10 64-bit machine. Once the installer is downloaded, go ahead and launch it and follow the standard setup steps. During the install, you will be presented with a choice to let DisplayCAL handle calibration loading:

I highly recommend to keep this option checked. After the installation is complete, go ahead and double click the DisplayCAL icon, which should be on your desktop. As soon as DisplayCAL main window comes up, you will be presented with the following notification:

Go ahead and click the “Download” button, which will start the download process of ArgyllCMS. Once the download is complete, DisplayCAL will automatically handle the proper placement of ArgyllCMS files and the above message will not appear again. Go ahead and close out of DisplayCAL – we want to make sure that it properly loads together with ArgyllCMS, but only after the colorimeter is plugged in.

Now go ahead and plug in the i1Display Pro colorimeter to your computer. As I have pointed out before, the first time you plug in the colorimeter, Windows may want to install it as a HID device. Let Windows do its job. I repeat this here because you may want to validate your monitor in another computer or OS than the one you use with DUCCS. Color Munki Display behaves in the same way, just plug & play. If you want to use i1Pro / i1Pro2, then a USB driver is needed, so make sure to check ArgyllCMS documentation.

The next step is to launch DisplayCAL again. With its default configuration (Settings: Current in the upper combo box), DisplayCAL reads information from default profile associated to a monitor in “Color Management” configuration of Windows Control panel. Validations will run against that display profile.

Before any measurements, you must configure i1Display Pro colorimeter to work with GB-LED technology. This is done with the help of GB-LED spectral samples bundled with DUCCS (or i1Profiler) software. ArgyllCMS knows how to convert SPD stored in “.edr” files from X-rite software to its own text format for SPD with “.ccss” extension. These files are known as “spectral corrections” for colorimeters. You can do this task via “Tools -> Correction -> Import colorimeter corrections from other display profiling software” menu entry. You will see a pop-up window like the following:

The “Auto” feature may find it automatically if DUCCS is installed in your computer (it did on my PC). If that does not work, then click “i1 Profiler” check box and upon “Select file” select i1Profiler setup executable (you might need to download i1Profiler setup from X-rite’s website). After importing spectral corrections for i1Display Pro, you must select “LCD RG Phosphor” (RG_phosphor_family_25jul2012.ccss) in the “Correction” drop-down, which stores a 1nm GB-LED spectral sample for White, Red, Green and Blue channels:

If you see an error related to unknown or unplugged colorimeter, make sure to navigate to “Tools -> Detect display devices and instruments” menu. I would make sure to enable “Options -> Show advanced options” too. The last check is to ensure that “Display” has your monitor selected and “Settings” are still kept at “Current” in the upper drop-down:

Measuring Uniformity

Always make sure that you buy a solid measurement device, such as the i1Display Pro colorimeter before you purchase a wide gamut monitor. The main reason is to measure monitor screen uniformity as it arrives and if it is bad or it does not suit your needs, return for a refund or an exchange. Perhaps an NEC Spectraview Reference PA or an Eizo CG have a superb uniformity out of the box, but we are talking about a very different price range here. In my Basics of Monitor Calibration article I wrote a brief explanation about measuring screen uniformity and what to seek, such as luminance differences (expressed in percent) and color differences (expressed in deltaC) of screen zones against the center of the screen.

DisplayCAL 3 offers a uniformity validation against ISO norm 12646. It will divide your screen in 5×5 grid and take a few grey and white measurements for each of these cells. Then you’ll get a PASS/FAIL (green or red color) report for each zone. It’s very unlikely that Dell, LG or BenQ or whatever cheap “XXX” monitor model will pass such tests without uniformity compensation features enabled, and if enabled, you cannot use them in CAL1 / CAL2 (Dell) or it may result in crippled contrast unsuitable for video. If you seek to pass that test as a mandatory requirement, then look for an Eizo CS240 or a high-end NEC PA or Eizo CG monitor.

What we can do is validate the much more affordable Dell models against reasonable “good enough” uniformity values for a monitor designed for photo editing or graphic arts. My criteria are to have overall good brightness uniformity with screen corners, which may go down to -10 to -15%, and color uniformity under 2 deltaC for all cells against the center. Some deltaC in corners may be a little higher than 2dC since that screen zone will be covered with menus, tools or whatever options your image editing software offers you. I certainly do not want a screen with patches over 3 deltaC, so I would return it without hesitation. And if there were too many cells near (or over) 2 deltaC, I would return such a monitor too. It is totally up to you – your mileage might vary. I find such requirements a minimum for a 400-600 dollar 24″ (1920×1200) or 27″ (2560×1440) Dell models. These are not ISO requirements for color critical applications and high-end monitors either, just “good enough” for a monitor of this price range that manufacturers must meet as a minimum.

For what I have seen in person or from owners’ uniformity reports sent to me, lots of BenQ SW2700PT, Dell UP2516D, UP2716D, “ALL” LGs and all bigger screen Dell models of the 2014-2018 family won’t meet even these “low grade” uniformity requirements. Most of them will fail, so return them for refund or exchange if they fail this easy test. It’s not your fault that there is such lack of quality control in these 2015-2018 models. The price of some models has not dropped from Dell’s 2013 models and lots of new models might even have worse quality at a higher price tag!

Uniformity measurements are under “Tools -> Report -> Measure display device uniformity”. A new window will show up with a 5×5 grid. You must remove your colorimeter’s hood and place the colorimeter over one of the grid cells. Then click on “Measure”. It will take a few grey and white color measurements. You must repeat the process for each grid cell, so that the whole screen looks like this:

When you complete all cell measurements a file dialog will show up, asking you to save the uniformity report. It will be an HTML file with some embedded Javascript functions, so you must enable Javascript on your internet browser to see the report. This report will show in a grid brightness and deltaE values for each grey and white, plus an average value for each cell and default ISO norm 12646 validation. If you click at each cell value you’ll see brightness and deltaC values (and delta Hue and other info too). Brightness in percent and DeltaC color deviations are what we previously discussed as “good enough” minimum uniformity requirements for these monitors:

Profile Validation

DisplayCAL provides a feature to validate any display’s ICC v2 profiles and generate an HTML report with results. Unlike other applications, this report also contains information to validate a “neutral grey” calibration or white point closeness to daylight or black body loci. So even if you have a very accurate profile that describes perfectly your monitor behavior (like DUCCS table profiles), DisplayCAL can evaluate if calibration is good (neutral grey to your white point) or let you check if white point is far from its intended value. DUCCS validation feature does not offer this kind of information.

To proceed with profile validation, click the “Verification” button in DisplayCAL. The content below will change and show you several fields:

Next, click “Measurement report…”. Just like before, it will ask you to name the report first, then once you select file destination and click “Save”, you will be presented with the below screen:

Place your colorimeter (with hood reversed) over that window. Once ready, click “Start measurement”. ArgyllCMS will show several patches of colors and measure their color coordinates with your device (corrected with GB-LED CCSS to be accurate). Darker patches need more time. Please don’t mess around with any applications or the Windows task bar until the whole process ends – you do not want anything influencing the measurements.

After the last patch measurement, your default Internet browser will open with the saved HTML report. Just like before, you must enable JavaScript to see this report.

HTML validation report is very self-descriptive, with labels and green/red colors. Just a few hints:

Given these indications, the HTML Measurement report is easy to read with lots of useful information not available with other software.

With this method, you can evaluate DUCCS calibration issues by yourself. You can validate hardware calibration and profiles from wide gamut NECs, Eizos (internal colorimeter in ColorEdge CG is not supported by ArgyllCMS AFAIK and may have backlight SPD slightly different from GB-LED), BenQ, etc… You just need to remember to apply GB-LED spectral correction before you measure (older wide gamut monitors may need WG CCFL spectral correction bundled with i1Display Pro software). It does not matter that you get “all green” results from Basiccolor, Palette Master, Color Navigation or Spectraview… if ArgyllCMS / DisplayCAL report an issue, you must put attention to it and examine what’s happening.

Remember that if you set a white point in Color Navigator or Spectraview software by “visual match” or by paper color measurement, you can ignore “Measured vs. assumed target white point ΔE*00” result because you didn’t aim for a daylight or blackbody white.

Without a new DUCCS version that actually fixes these issues, you will need an AMD / ATI graphics card (Radeon or Firepro) or an NVIDIA Quadro to fix these grey range and white point issues with a GPU LUT calibration. With that hardware, GPU calibration will correct white point if needed and get perfect neutral and smooth grey gradients akin to a high-end hardware calibration. This is possible because of high bit depth dithering LUTs inside those graphics cards AND dithering. “Dithering” is a very important feature to encode high bit depth results into graphics card output, as explained before. Later on, you will see how to do this with ArgyllCMS / DisplayCAL.

Update: It looks like the new Geforce 1000 series video cards can be bandless even on extreme GPU white corrections after Mr. Gill patched some issues for NVIDIA in ArgyllCMS 1.9.x. While I have not had a chance to test it, the information seems reliable and Mr. Gill actually changed the code for VCGT profile tag loading into GPU LUT. This only works with DisplayPort or HDMI connections, more than 8bpc configured in nvidia control panel and a monitor that can accept more than 8bit. Otherwise banding is very likely to appear.

Older NVIDIA GeForce or Intel integrated graphics unit (iGPU) won’t be able to fix this issue without suffering banding artifacts in some places of a grey gradient… unless before GPU calibration you have a nearly perfect grey, so you don’t suffer from DUCCS issues and no GPU calibration is needed.

Laptop users are unlikely to be able to fix it, since even with a dedicated Quadro or Radeon GPUs, the HDMI / miniDisplayPort / Thunderbolt outputs on most laptops are driven by Intel iGPU (for Intel laptops) with its low bit depth, ditherless LUTs. This is because laptops are designed to be power-efficient, so a dedicated GPU switch on/off only to assist with calculations and all outputs are driven from iGPU LUTS which are always on. There are some laptops with outputs driven by a dedicated GPU – ask your laptop manufacturer for more detailed information.

Re-profiling

DUCCS can make two kind of profiles:

Your CAL1 or CAL2 calibrations may not have a very good grey range, so with accurate TRC profile info, gradients may look neutral with Photoshop color management. That means you need a DUCCS table profile, but you may want to use it with other “non X-rite table ICC compatible software” so this is not a viable option.

There is a solution, to let ArgyllCMS re-capture monitor behavior in a profile without GPU calibration. ArgyllCMS / DisplayCAL offers you a bigger catalog for profile types than DUCCS:

Keep in mind that LUT profiles need a huge number of measurements to be accurate. You are going to capture monitor behavior (CIE XYZ coordinates) for a large set of RGB inputs. This can be visualized like a cube table, a 3D table. For 5 measurements per cube side (5 measures from black to red, 5 from black to green, etc), you need 5x5x5 = 125 measurements to map the whole cube, the whole display gamut with a 4 step cube side. For 10 measurements per cube side, you’ll need 10x10x10 = 1000 measurements. For 15 measurements per channel, you’ll need near 3400 and for 20 it grows to 8000 and so on. Some inner cube measurements can be skipped of course – this is just an easy explanation that for a tiny increase in cube resolution, a huge increase in total measurements is needed.

That translates to more time and that’s easy for a fast device like i1Display Pro, but if you have to measure with thousands of patches with a Munki Display or an i1Pro2, you will need a lot more time. I wasn’t joking when I said that if you need to profile printers, measure fabrics’ color and calibrate displays, you should get both devices: an i1Display Pro and an i1Pro2 (or a used i1Pro for a low budget). It’s not just a matter of speed but of accuracy too as explained before.

DisplayCAL 3 and DispcalGUI 2.6 can do profiling without calibration, but IMHO this is faster and easier to do with DispcalGUI v2.6 because it has a button for that. With v3 you need to change calibration target to “native” in several user interface fields (white point and gamma) and disable interactive adjustment. For this feature, DisplayCAL 3 should have a button just for “profile”, without calibration.

In the “Profiling” block you can configure your desired profile type. A “Curves + matrix” would suit your needs and take less time to do: your display is already calibrated in a LUT3D. Set “Profile quality” to “high” and enable black point compensation (BPC). BPC means that the resulting profile will store a near perfect black behavior. This is less accurate than a measure of your actual black point, but this way color-managed applications will color manage “less” near black colors, so you avoid black crush and dark grey “tint” issues. Black crush issues could be caused because profiles like AdobeRGB have an ideal infinite contrast, its black is a “true black”, so if a color-managed application sees that your display profile darkest black is for example about 0.12cd/m2 (1000:1, 120cd/m2 white), it will crush to R=G=B=0 any color, whose color coordinates are darker than this 0.12cd/m2 black point. You may lose several dark grays, all crushed to your display R=G=B=0 black value.

Dark grey tint could be caused by inaccurate low light measurements of TRC while profiling, so it’s safer to assume that a* and b* color coordinates for near black grays are 0, colorless, so this is another BPC advantage.

XYZLUT profiles could use BPC too. Some advocate against its use in these “table” profiles, because they are meant to be “accurate” but if after profiling a non-BPC XYZLUT profile you notice those kind of issues in Photoshop or similar color-managed programs (dark grey color tint), I would go for a BPC version of your current profile without a doubt.

It is very important that if you choose to create an XYZLUT profile, then click on the gear icon and make sure that “Enhance effective resolution of colorimetric PCS-to-device table” is enabled and “Smoothing” must be enabled too. Otherwise Photoshop and other programs may show “brightness waves” in color gradients.

Next, you should select the test chart for profiling, the set of color patches to be shown in your display and measured by your device. DisplayCAL 3 has an auto feature but you can also copy old charts from DisplayCAL v2 (DispcalGUI) to v3. I would go for “Extended testchart for LUT profiles” that has a total of 175 patches, since you may want to capture the grey range issues that DUCCS cannot solve. You should know that your display might not have a perfect grey, so you want accurate TRC for your display profile.

Name your profile. The default input field for name will account for current “calibration” target (white, gamma, etc), change them or erase those parameters.

After all the measurements are done, ArgyllCMS will compute a profile. When profile is complete, a summary pop-up window will be displayed with sRGB and AdobeRGB intersection with your profile. You can inspect its gamut, TRC and other profile information. Just check “Show profile information” if you want to see that info:

There will be a button for installing the profile on your OS and a selection to install the profile for current user only or as system default.

Make sure that after profile installation you change DisplayCAL to “Settings: Current” (upper combo box).

GPU Re-calibration

If DUCCS is unable to give you an acceptable white point or grey range, then you can fix it with calibration curves in GPU LUT. If your DUCCS calibration is OK, skip this section: you don’t need it. As discussed in previous sections, you’ll need an AMD / ATI graphics card or a NVIDIA Quadro (not NVS Quadro) desktop graphic card versions (NVIDIA GeForce 1000 series are an exception). Without this kind of hardware, you may get banding artifacts (I mean you WILL get banding artifacts because you have color tint issues on grays right now). First of all, you must need to know that white point GPU LUT correction lowers maximum brightness output, since we are going to limit one or two channels max output to get your desired white. With GPU re-calibration, you may fix the white point in factory calibrated OSD modes like sRGB or AdobeRGB.

GPU re-calibration is only about white, neutral grey and gamma. You won’t alter your current CAL1 or CAL2 gamut emulation. You may want to disable “Interactive display adjustment”, because you cannot change OSD settings – the same applies to sRGB or AdobeRGB factory calibrated modes.

Change “Whitepoint” to your desired target. For example, 6500K daylight (D65), or 5000K daylight (D50) or CIE xy coordinates of your paper white. No “Visual match” is allowed here, because you cannot change your current monitor’s white with the OSD buttons in your screen for CAL1, CAL2, sRGB or AdobeRGB modes.

Leave both “White level” and “Black level” “As measured”.

For “Tone curve”, select your intended TRC for CAL1 or CAL1 in DUCCS, but for constant gamma values use “Relative” setting.

Do not use “Ambient light level adjustment”, since DUCCS does not use it either (it’s out of the scope of this mini-guide, check DisplayCAL documentation).

I would configure calibration speed to “Low” and leave other calibration options as default.

Some of these options are available only if you enabled “Show advanced calibration options” under the “Options” menu.

For profiling options choose whatever you want, “Curves + matrix” configuration described in previous section will do the job.

Click “Calibrate and profile”. If you didn’t disable “Interactive monitor setup”, click on continue, you cannot change RGB gain and offset controls for CAL1 or CAL2:

Calibration process in ArgyllCMS is an iterative process of measuring monitor’s native TRC and trying to correct it. With each loop, more measurements are taken, narrowing the step gap between measured grays. In the last iteration, up to 96 grey measures are taken to ensure accurate calibration curves. This is a big difference when compared to DUCCS.

When this process is finished, ArgyllCMS will compute calibration curves from measurements and load them into your GPU LUT. At this point, your display is calibrated in GPU LUT, but you need an accurate profile that describes this calibration. Like in the previous section, ArgyllCMS will measure monitor behavior, compute a profile and embed your new calibration curves into it.

When profile is complete, a summary window will show up with sRGB and AdobeRGB intersection with your profile. If you check “Show profile information”, you can inspect gamut, calibration curves (which now won’t be linear), TRC and other profile information.

Just like before, there will be a button for installing the profile on your OS and a selection for installing it for the current user or as system default. Pick the appropriate setting and install the profile.

Make sure that after profile installation you change to “Settings: Current”.

If you chose to use DisplayCAL / ArgyllCMS LUT loader, it will start on user logon. It will check what profile is set as default in OS color management.

If you want a full GPU LUT calibration you can get it in the same way under “Custom color” OSD mode (full native gamut). This way, you can access RGB gain and offset OSD controls of your monitor. ArgyllCMS has no DDC / CI support, so you must manually configure those controls using the buttons in your monitor.

Make sure to enable “Interactive display adjustment” and when prompted for whitepoint adjustment, remember to lower / raise brightness control as you change RGB gain control until you get your desired whitepoint, white level and contrast.

Again… make sure that after profile installation you change to “Settings: Current”.

These GPU calibrations and profiles could be validated in the same way as DUCCS profiles.

That’s all there is to it! If you have any questions, please feel free to ask in the comments section of this article.

Disclamer:
This article was originally written in 2016. There are now new models in premium and non-premium market segments. More monitors are out of production like Eizo CS240. Now in 2018, the same uniformity issues we described for Dell or BenQ Or LG wide gamuts are still there in new models so be warned about non-premium wide gamuts.

NEC PAs or Eizo CS models have lower prices than when 2013 Dell’s GB-LED came out. I’ll choose a NEC PA or an Eizo CS/CG over a bigger resolutions model from Dell, BenQ, LG, Asus or any of these brands for the same price range. More resolution does not translate to a better monitor.

You won’t be able to correct uniformity like we fix DUCCS problems with DisplayCAL, it will stay there for all monitor’s life and as the monitor ages, it will get worse. Final choice is up to you, but my recommendation is to avoid low-cost models and get an NEC or an Eizo if you want a real wide gamut monitor.

This article has been submitted by a guest poster who wanted to remain anonymous. He goes by “Color Consultant” nickname in articles and forums at Photography Life.

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