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For my curiosity, I decided to Reset the monitor…
See attached OSD screen capture :
– Brightness and Contrast = 75% each
– Gains @ RGB = 255 255 255White (As measured)
Chromaticity x 0.2668 y 0.2770
CCT 12952 K
Luminance 270 Cd/m2Black (As measured)
Chromaticity x 0.3114 y 0.3352
CCT 6547 K
Luminance 2.46 Cd/m2What do you want me to do next?
I think I remember having these “Offset” controls on my old Mitsubishi 900u.
They controlled the Black point “chromaticity”.Roger, some of your responses have mixed up comments from Vincent and me.
I want to repeat some points to be completely clear.
We all assume you want to maximize the performance of your display. This means dialing in as much calibration as you can via the displays onboard controls before profiling. But it also means avoiding where those controls may harm performance (per Vincent’s “you’re doing it wrong comments).
So to review the proper approach:
LCD DISPLAY NATIVE WHITE
An LCD display white is fundamentally determined by its backlight color. Today the industry is converging on D65 backlights, although with very different spectra depending on the technology.
I1DISPLAY COLORIMETER CORRECTION FOR BACKLIGHT SPECTRA
The i1Display is generally regarded to be the best choice for speed and accuracy, but because it takes a visual measure, accurate readings may require a correction for your display backlight. You previously reported you are made your own CCMX correction. This should be good assuming you do it correctly. If you are uncertain, the DisplayCal database has lots of CCSS for you to draw upon. CCSS is generally applicable to the display backlight type, CCMX can be more accurate but is only applicable to the specific display it was made for. Both are only as good as the spectro used to make them and the competency of the maker.
SETTING DISPLAY TO CUSTOM TEMPERATURE
To hit your target white you have to face the physics of LCD: you can only do it by reducing the LCDs aperture (gains is a misnomer) for R / G / B— you can’t raise these. (Unless the designer of the display did something very wrong, which from Dell is unlikely.)
Part of good display performance is not compromising peak luminance nor contrast. If you want to preserve this performance, you do as little reduction of R / G / B as possible.
Every temperature can be reached with one of R G or B at max. So finding desired white is a simple process of triangulation with the help of your meter to find the balance. You start with all R / G / B at default. To get yellower than native (D65) you close the aperture for B and G. To get bluer, you close R G. In order to stay on the Daylight locus, you need some freedom to go up or down on G. You can achieve this by either raising G, or lowering R and B.
Vincent points out that some displays have weird R / B / G controls that allow you to raise past clipping. This must be avoided. You can use a test pattern like those found at lagom.nl black and white tests on your uncalibrated display (empty VCGT) to explore the display controls.
Once you understand the physics and controls, the process of hitting your desired temp using the display controls becomes obvious. You should not require VCGT to hit target white unless your display doesn’t have true gain controls, or if the granularity of the control is lower than the data path to the display (e.g. 8 bits). Dells typically do have true LCD gain controls which are at max by default,, but the granularity may vary.
Use DisplayCal’s calibration assistant with visual daylight temperature (VDT) readout to help find the best fit white to your target white via the display’s gains. Then, if you are happy with result, choose native white in when profiling, or if you want to employ VCG to seek a closer match to your target, enter your target white for the profile and DisplayCal will try to improve the calibration with VCGT.
Once calibrated, you use the display’s backlight control to set target luminance. If you want highest white precision at a target luminance, use the backlight to set luminance before profiling. (I choose to set white based on mid output and use backlight control for various viewing conditions and find it very useful in place of a controlled environment.)
Leave the display’s other color controls at factory default unless you have a good reason for changing them.
Dear Wire,
Do keep in mind I don’t use the i1display3 for these adjustments as I have my trusty, old Minolta CS-200 chroma meter.
So I resetted the monitor completely.
Step 1 Full RGB “Gains”, Brightness / Contrast @ 100
White 12088K 355 Cd/m2Step 2 Same as Step 1 except Contrast @ 50
White 12419K 190 Cd/m2Step 3 Same as Step 1 except Contrast @ 75
White 13026K 352 Cd/m2…. Brought Blue channel down progressively from this point on
Step 12 Blue is now at 50 (on the OSD)
Red and Green still @ 100
White x 0.3472 y 0.4992 5173K 337 Cd/m2
Black x 0.3118 y 0.3585 6406K 1.61 Cd/m2See? I am very close to D50 chromaticities.
What should be the next step up?
Keep in mind, I can’t work at 337 Cd/m2.So should I bring Contrast down, from 75 to…?
At this
1.61 nits black is what you measured in the native mode or after severely increasing the brightness?
Step 1 Full RGB “Gains”, Brightness / Contrast @ 100
As previously mentioned, you have to explore what the controls do. There’s all sorts of history including strange design choices that cause odd behavior.
So controls at 100 are not necessarily what you want.
You are looking max native response, meaning white is the color of the backlight with LCD aperture fully open at input 255/255/255, but not clipping.
Establishing native performance is crucial. If you’ve been changing controls to learn, you may want to restore factory default just to be sure of your baseline before doing real calibration.
If you measure native white as other than roughly 6500K that suggests it’s in an unwanted mode or poorly aligned at factory.
While you are at it: Double check your input settings in Dell to ensure you are in RGB mode not YCC, and also in the most native color mode, with PC gamma.
—As a personal sob story: When I last bought a pair of Dells, one was physically broken in shipment and the replacement sent was a refurb with wildly wrong presets. But I figured out its native mode was ok and that’s all I care about. Later I found a service menu and was able to partially update its preset calibration, but I lack the service tool needed to fully calibrate all presets. The point of this story is it’s important to learn to use the display as a tool.
Roger BTW— You appear to be using a Windows tool that talks DDC/CI to access your display controls. Be sure it’s not distorting the defaults— like it would be bad if the display’s factory default R / B / G were say 50 (for some crazy reason only Dell knows) but the control panel sets them to 100 for some reason only it’s developer knows.
Wire,
You wrote :
If you’ve been changing controls to learn, you may want to restore factory default just to be sure of your baseline before doing real calibration.
But I *did* write (didn’t I?) that first thing I did was to “Reset” the monitor to factory state.
I noticed a “difference” between MonitorDDC and the OSD control.
Like Blue “Gain” @50 is reported as Blue = 196.
I don’t really care if it’s not a linear scale.It’s ok to reset more than once as you experiment!
It’s merely a question of a consistent baseline.
Roger, according to the Dell user guide for your display, the Brightness control (little sun) controls the backlight intensity. The contrast control default is 75. In my experience, above default it expands mid-tone contrast by clipping highlights and shadows. Below default t compresses contrast by not using the full panel range.
The R / G / B custom color control is described as letting you set a custom temperature, but defaults are not listed, so you’ll have to experiment.
Get a white patch test pattern (ensure VCGT is not affecting white) and verify that these controls don’t clip above some level.
Did you write that you measured 12000K with R / G / B at max— I would not expect that behavior! If so, that’s a mystery to me.
After much sweat, this is what I’m going to calilbrate / profile upon on this gorgeous 42″ Dell U4236Q display :
Brightness 75
Contrast 50
Red 100 Green 76 Blue 59White Point : x = 0.3460 y = 0.3524 / 4968K / 92 Cd/m2
Black Point : x = 0.2960 y = 0.2834 / 8476K / 0.6 Cd/m2Honestly, I don’t think I’ll go for full Black correction as that will bring the contrast down to much, at the expense of neutrality in the shadows.
I am satisfied for now. I rest my case.
Good stuff you are making progress….
Brightness 75
Contrast 50
Red 100 Green 76 Blue 59That Contrast control setting is unnecessarily sacrificing contrast.
As I mentioned a couple posts ago, I checked the users guide for your display and noted the default setting appears to be 75. And it so happens that on the Dells I am using the default (native) contrast control 75. I have checked this with a test pattern.
White Point : x = 0.3460 y = 0.3524 / 4968K / 92 Cd/m2
Black Point : x = 0.2960 y = 0.2834 / 8476K / 0.6 Cd/m2And as you can see your effective contrast is
92/0.6 = 153:1
The panel should yield ~ 1000:1
That’s sacrificing almost 3 stops of dynamic range!
But if you are primarily interested in print with a light booth next to display, maybe this is what you want because you’ll be visually adapted to the booth?
Carry on
350 cd/m2 is way excessive for my applications, Vincent. The first time I ran into 350 cd/m2 was on an Apple Cinema Display 10 years ago. I thought that was “brutal” but then again, it was using right next to a window, in almost “broad daylight”.
No way I’ve recommended such thing. I ALWAYS wrote “white level = OSD brightness”
What I am saying is that droping 50% in brightness due to RGB gains and only that (like in your setup) is an abnormal configuration, that something has been pused down too much or that RGB gains behave wildly over some value due to poor electronics control or whatever.In the end, EVEN if I find a G+B gain combination that preserve much of the original brightness on this monitor, do you really think I am going to “keep” whatever resulting Luminance level that way?
As said many many many times before, that you may have not read, “white level = osd brightness”.
But since you have to drop from native white to D50, leave some headhroom on a “normal behaved display” like 140 so RGB gain drop will give you 120 or values like that.
