Wide Gamut and Windows 7

[Caleb]

Hi,

I've been reading about the problems with wide gamut displays recently, and how they make everything look over-saturated. I've never known about this before, and now I can finally understand why the Dell 2408WFP looks so eye-popingly "bright".

Since pretty much most of the new 24" monitors coming out right now are touting wide gamut, I'd really like to know how one could get around this problem of over saturation on the Windows desktop.

A few questions:

1. Will calibration using a calibration software+hardware tool help alleviate the over-saturation in every program in Windows 7?

2. I've read in the forums that color profiles only work in color-aware applications, but that doesn't make sense. Why would a global-wide Windows profile work only in color-aware apps and not everywhere? I'd assume that it overwrites the LUT or something and then everything is fixed, no?

3. If the answer to #2 is that system-wide color profiles in Windows do not work in all applications, are there 3rd party apps to force a color profile on everything? (PowerStrip maybe?)

4. On this page of the new Dell 24" http://www.dell.com/us/en/dfo/peripherals/monitor-dell-u2410/pd.aspx?refid=monitor-dell-u2410&s=dfo it says 2 things which are confusing me:
a. "110% Color Gamut (typical)"
b. "Compatible with Industry Color Standards: 100% sRGB, 96% AdobeRGB"
What is the gamut that is being referred to in (a)? Because in (b) I guess they're talking about percentage of the sRGB and AdobeRGB gamuts.

Thanks!

 

[10e]

1) Calibration will properly re-map the three color primaries to achieve more consistent color brightness/gamma but it will not reduce the over saturation associated with wide gamut color primaries. A wide gamut monitor in native Adobe RGB mode will still have overly strong colors, especially red and green. Only in color managed applications will gamut "transformation" be achieved and sRGB tagged photos will look sRGB, and thus, not look overly/unnaturally colorful.

2) A color profile will only work in color managed apps in regards to remapping a wide gamut monitor to a smaller color space like sRGB. In Windows, if the ICM profile is loaded into the graphics card LUT, or color look up table, it will adjust the gamma of colors to (again) achieve color brightness consistency, but not reduce over saturation.

3) No, not to reduce over saturation in general. Same as answer 2). Powerstrip will only preserve color adjustment in 3d apps where normally they are cleared from the graphics card's color LUT (lookup table), I've heard Monitor Calibration wizard 1.0 can do this too, but I could be mistaken.

4) The U2410 is a wide gamut display that seems to have an effective sRGB mode to reduce the over saturation from what I've read. A number of other wide gamut displays like the Dell 2408WFP, 2709W, and the HP LP2475W have sRGB modes, but they are not very accurate and overly under saturate colors.

 

[brumwald]

I might be wrong on the details (please correct me) but heres the general gist of it.

1. No

2. What gets overwritten in the LUT (and this affects all applications) is the gamma calibration (correct me if I'm wrong here), and that has nothing to do with gamut. Thus you will still benefit from a color profile in all applications - but the wide-gamut issues are still there. What color-aware applications do is to take into account what gamut your monitor(/profile?) has and translate everything into that color space.

3. Unfortunately, no.

4. When only a percentage is shown it's usually meant to be NTSC.
72% of NTSC ~= sRGB if I'm not mistaken. sRGB is a bit smaller than what most are used to though, so it often looks a bit dull in comparison to a "regular non-wide-gamut monitor".

What makes the U2410 unique is that there might be a decent sRGB mode where the monitor does the translation and all applications will look OK. The sRGB mode will basically make the monitor non-wide-gamut. Not completely without issues though depending on the implementation. And the sRGB mode is not unique by any means, it's just that most (all? ) implementations of it so far have been quite poor, or how should I put it, useless... The U2410 might do this well but since it's so new I haven't seen any in-depth review of it.

 

[Caleb]

1) Calibration will properly re-map the three color primaries to achieve more consistent color brightness/gamma but it will not reduce the over saturation associated with wide gamut color primaries. A wide gamut monitor in native Adobe RGB mode will still have overly strong colors, especially red and green. Only in color managed applications will gamut "transformation" be achieved and sRGB tagged photos will look sRGB, and thus, not look overly/unnaturally colorful.

But if it revamps the color primaries, wouldn't that result in a less saturated image all around?

2) A color profile will only work in color managed apps in regards to remapping a wide gamut monitor to a smaller color space like sRGB. In Windows, if the ICM profile is loaded into the graphics card LUT, or color look up table, it will adjust the gamma of colors to (again) achieve color brightness consistency, but not reduce over saturation.

I don't understand this. A color profile is supposed to define the color space of the device, right? So what does it have to do with gamma?


This is what I understand about this so far, please correct me if I'm wrong:
Wide gamut monitors have primaries that are more saturated than the normal gamut monitors which lead to improperly displayed colors in applications that do not to gamut transformation (for example, non color-aware browsers will show most images on the Web incorrectly on wide gamut monitors because they are mostly untagged sRGBs).

A color profile is supposed to define your color space, so if you use a proper color profile with your wide gamut monitor, any application that is aware of this profile and knows how to do do the conversion properly will display colors properly. Applications that are unaware will be overly saturated.

Is it even possible to fix this problem at the OS level only? It seems to me that the only system-wide fix possible is to force everything into sRGB, and not be able to enjoy both worlds.

 

[Caleb]

4. When only a percentage is shown it's usually meant to be NTSC.
72% of NTSC ~= sRGB if I'm not mistaken. sRGB is a bit smaller than what most are used to though, so it often looks a bit dull in comparison to a "regular non-wide-gamut monitor".

I thought that both LCD TVs and PC Monitors used sRGB (and thus assumed that they have similar gamuts). Do LCD TVs have wider gamuts?

 

[brumwald]

I thought that both LCD TVs and PC Monitors used sRGB (and thus assumed that they have similar gamuts). Do LCD TVs have wider gamuts?

I thought so too but to me it seems to me as if sRGB in contrast to a 'regular' display looks quite dull. Perhaps the oversaturated-color trend started before actual wide-gamut displays.

HDTVs are moving towards wide gamut as well (if I only could understand why) and even if they are not wide gamut they are often tuned to give oversaturated colors. All this and a really strong backlight just to look good in the store...

 

[Sailor_Moon]

Do LCD TVs have wider gamuts?

In most cases: Yes. But the manufacturers implement modes that limit the color space towards sRGB (Rec. 709 (=> HDTV) defines the same primaries - and definitions for PAL/ NTSC are not too far away). If the TV implements what I would call "a full featured CMS" you can raise the accuracy. But such TVs are quite rare. The solution can be a videoprocessor with a build in CMS. The Radiance from Lumagen is a good example because it has a "full featured CMS": Based on the native color space of my TV I was able to calibrate it very close to PAL and HDTV sources.

Best regards

Denis

 

[Whoisthisreally]

Okay, I think I've got my head wrapped around it enough to try and answer your questions. Enraged ICC members, feel free to boot me.

I don't understand this. A color profile is supposed to define the color space of the device, right? So what does it have to do with gamma?

Simplified, a monitor ICC profile holds three sets of data. The first one is a 3*3 matrix that records the chromaticities of your monitor. The second one is a one-dimensional Tone Reproduction Curve, one for each color. This set of data can be loaded by your Video card to achieve a target gamma. The third set of data is a three-dimensional lookup table, or a color lookup table (CLUT). This data allows us to perform color transformations, such as saturation adjustment.

Wide gamut monitors have primaries that are more saturated than the normal gamut monitors which lead to improperly displayed colors in applications that do not to gamut transformation

Wide gamut monitors have chromaticities which are different compared to an sRGB monitor. Reducing the brightness of a color in this case will not result in a color closer to a smaller gamut. The difference of colors between gamuts is measured in saturation, thanks chklin, which involves not one but all three colors in a saturation transformation (source here):

R255G0B128, 100% saturation

R192G64B128 50% saturation

R160G96B128 25% saturation

Your color managed software uses the recorded RGB chromaticities, CLUT and reference colorspace profile (such as sRGB: these profiles are included in the program) during gamut mapping.

If you have a monitor with an internal 3D LUT, it should be able to do its own color transformation if you feed it the profile through DDC/CI. The U2410 seems to have an internal sRGB profile calibrated from the factory, but we don't know how robust and configurable the implementation is.


There is an interesting piece of color management software in the form of a patch for mplayer. written by a person called Yue Shi Lai, it accepts an ICC display profile and displays the video to the target of hard coded video broadcast standards. Definitely great news if you ended up with a WG monitor.

 

[Snowdog]

4. When only a percentage is shown it's usually meant to be NTSC.
72% of NTSC ~= sRGB if I'm not mistaken. sRGB is a bit smaller than what most are used to though, so it often looks a bit dull in comparison to a "regular non-wide-gamut monitor".

Not really. Before the wide gamut craze, just about everything was essentially sRGB. TV is just about sRGB, HDTV standard is almost exactly sRGB, most CRTs are right around sRGB.

You can look at the color triangle of older monitors before the wide gamut craze and they were all very close to sRGB.

If anything most still fell a bit short of sRGB.

I have had multiple CRTs, 5 LCDs (1 wide gamut, 4 normal) and they all look very similar nothing dull about my latest NEC 2490 that is nicely calibrated and very close to sRGB (possibly a bit short of sRGB in fact).

What is often dull and poor looking is the sRGB modes in past wide gamut monitors. These have pretty much a disappointment so far. That is why I remain skeptical about the sRGB mode.

Nothing Dull about sRGB unless you are used to wide gamut running in uncorrected mode.

 

[brumwald]

Ok, makes sense.
My experience mainly comes from non-wide-gamut monitors (consumer level) which have had a sRGB mode. And in those cases it often looked quite dull in sRGB. Maybe they thought it was justified to mess around with the standard mode if they offered an sRGB mode

 

[Sailor_Moon]

The second one is a one-dimensional Tone Reproduction Curve, one for each color. This set of data can be loaded by your Video card to achieve a target gamma.

The TRCs only reflect the current gradation of your display (e.g. if you choose a gamma of 2.2 while your calibration, this value is noted there for each primary; so the calibraton must ensure that this gradation is actually achieved). They are used -together with the 3x3 matrix that is created based on the tristimulus values of the primaries (which are stored separately in a matrix ICC profile)- by a CMM to transform in the PCS and from the PCS to Display-RGB.

The correction for the Video card LUT (in particular to achieve the desired gradation and neutral greyscale related to the whitepoint) is again stored separately and can be loaded by an auto loader tool at startup.

The difference of colors between gamuts is measured in saturation

It is not only saturation. Regarding green the difference is mostly hue.

Best regards

Denis