Why does using “sRGB” as my monitor display profile look better than the built-in profile?

Question

I've got a (2013) MacBook Pro. I also have an ASUS VS248 secondary monitor.

When I first plugged it in, I found that the greens were washed out and the browns had a red tint. I switched it from the "VS248" profile it was on to the generic "sRGB IEC61966-2.1" profile in System Preferences and it looks much better, nearly matching my (factory-calibrated?) internal display.

I know everyone says not to use straight sRGB as a device profile. So why does it look so much better that way? Can straight sRGB be a better choice than the profile the monitor comes with?

_{I don't know the panel type of the secondary monitor. My internal display is LED-backlit IPS.}

Answer 1

The general advice not to use sRGB as a device profile stems from the fact that it is not meant to be a device profile. When people start doing colour management, they often get confused about all those profiles: as a minimum, one needs at least two, and sometimes four or more. Drilling that sRGB is not a monitor profile helps to clear things up a bit.

However, it is not impossible to have a monitor that matches sRGB. In fact, sRGB was developed (partly) as a simplified analytical model of an average CRT monitor (and now LCD monitors have to mimic its response). This is like having a box 1 yard long: you can use it as a yardstick (literally), and you can even call it your yardstick.

This is regarding assigning sRGB as a monitor profile. Usually it's a mistake, but if you know what you are doing, it's not necessarily wrong. Now, how do we know the truth? What is more wrong: your laptop or the monitor?

Well, without a colorimeter, or at least a calibrated system side-by-side, we don't know. If you try to use your visual judgement, beware: our eyes are highly adaptable, and what we've seen most recently (for some time) might feel 'right', even if it isn't. Moreover, the correct calibrated colours may easily seem duller, off-balance, in a word, worse, than the uncorrected colours. Colour management is not about 'better' colours, it's about correct colours.

Nevertheless, in your particular case, if you can't buy/hire/borrow a colorimeter, I would trust your MacBook more. If you only want to match colours between the two, just keep that sRGB monitor profile.

I don't have first-hand experience with MacBook Pro and don't know how well they are factory calibrated, but we know that 1) Apple does invest some effort in colour calibrating their products; and 2) IPS display is vastly superior to any TN in terms of colour reproduction. The difference is such that I would have an aged IPS over a new TN any day.

Your laptop has a respectable age, but in my experience (a decade of checking and re-calibrating IPS monitors) IPS panels stabilise after about a year/1000-2000 hours or so. When new, they do require re-calibration every ~2 weeks, but in later life re-validation didn't require calibration for 2-3 years in a row!

Moreover, I generally don't trust any stock profile, and this particularly applies to TN monitors. First, the manufacturers know that nobody does any colour-critical work on them, and providing a profile is more of a token gesture. Second, the variation between the samples can be enormous. I have two 'identical' Acer TN monitors in front of me (at work) from the same batch, which I tried to match using a colorimeter. The worst difference in their colour settings (the blues level) is over 10%, and without correction, the colurs were very different between them.

Answer 2

Let's step backwards a bit and answer some "unasked" questions first:

1. What is a color profile.
2. What is a "monitor" profile and hardware calibration vs a "Factory Profile."
3. What is color constancy.

(I will make the assumption that the OP has not calibrated his monitors using "expert mode" nor a hardware calibrator.)

WHAT IS A PROFILE

ICC profiles are just a description of a way to transform color data. Put another way it describes how, within the ICC system, a specific color value should appear. For instance the hex color value #00FF00 means maximum green. But just how maximum? Maximum green is DIFFERENT depending on the color space. ICC profiles are the "treasure map" for where to find what such-and-such a color value relates to in terms of appearance.

Here's an example: The first patch is hex #00BD00 in sRGB, the other patches show what the hex value #00BD00 looks like when you send that number WITHOUT CONVERSION to those three other colorspaces:

Put another way, #00BD00 in Rec2020 looks like #00CF00 in sRGB, and #00BD00 in ProPhoto looks like #00DD00 in sRGB.

ICC profiles and color management take a particular VALUE as it RELATES to a particular COLOR SPACE and then coverts the value to what it needs to be in a DESTINATION color space.

WHAT IS A MONITOR PROFILE AND CALIBRATION

A Monitor Profile is a profile that ideally is based on the actual measurements of the color properties of a particular monitor. The idea than is the color management software knows how a value of #123456 should appear on that monitor, relative to some reference color space.

Hardware Calibration means the monitor's controls have been adjusted to a particular specification with the help of a colorimeter such as an X-Rite i1 DisplayPro.

Hardware Profiling means that the colorimeter and software has created a profile specific to that particular monitor.

A Factory Profile is typically a generic profile based on a brand-new version of a particular monitor model. The profile is likely made on a prototype under laboratory conditions. The chances it actually matches a particular monitor are somewhere between "slim" and "LOL NOT."

WHAT IS COLOR CONSTANCY

Human visual perception is not even remotely uniform. It is relative, and non-linear. Perception of a particular color is highly dependent on the surrounding colors and environment.

See this well known optical illusion:

The hex values for BOTH square A and B are #6F6F6F, yet A is perceived as much darker than B due to the relative surrounding image.

This applies to monitors in a big way. Two different brands side by side will rarely match. But either one in isolation will probably look correct.

(Nevertheless, one with a significant color or gamma error will likely end up causing images edited on it to end up a bit off.)

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How This Applies to the Question

OP has a few things going on:

1. A MacBook with a glossy screen that is using Apple's factory calibration.
2. An old ASUS monitor which probably has a matte screen and has not been calibrated nor profiled using a colorimeter.
3. A factory profile for the ASUS that is probably irrelevant.
4. Ambient light that could be incandescent? (3200K).

Color constancy causes the appearance of one monitor to affect the perception of the other monitor.

The monitors are unlikely to match. The monitor with the matte screen will also be affected by ambient light differently than the gloss MacBook screen, and if incandescent lighting is used may appear more orange or brown.

MacBook glossy screens tend to lean toward blueish. Also, they can be perceptually more contrasty than matte screens.

Both screens are of a different age/operating hours. LCDs shift yellowish with age.

The sRGB generic profile is essentially a "straight through" profile, sending values to the external monitor "essentially unchanged" if you are working in a sRGB space.

As it happens I am typing this on a 2013 MacBookPro.

What profile is selected for your laptop screen? "Color LCD" (i.e. the standard that ships with the laptop)? If you look at the curves in that profile you will see they are all three fairly different, especially the blue.

If you use EXPERT mode to calibrate/profile the MacBook, the resultant curves will be WAY different (and far from uniform). Here's the blue curve from the last time I did an "expert mode" non-hardware calibration of this laptop:

This calibration/profile was in the room light I normally use. I do have hardware colorimeters, but for MacBooks with glossy screens they don't seem to work particularly well.

As such, in your case it would appear that sending plain sRGB out to your monitor is closer in tone to your current MacBook.

You might try using expert mode to profile both monitors. TO access it, in system preferences select Displays -> Color, and then hold down option while selecting "calibrate".

You can also look at your profiles in Displays -> Color by clicking Open Profile, and taking a look at the resultant curves.

Answer 3

The question really revolves around whether you want your monitor to look "better" or more accurate. Let's unpack a few things.

... nearly matching my (factory-calibrated?) internal display.

Even if your display was perfectly calibrated when it left the factory in 2013, it's not perfectly calibrated now. Displays need to be regularly calibrated as they age. In a fully color managed environment, this should be done every 2-4 weeks.

When I first plugged it in, I found that the greens were washed out and the browns had a red tint.

If you have been editing your images to look the way you want on an increasingly inaccurate display (your MacBook Pro's screen), then you need to make the new display equally inaccurate in the same direction as your internal monitor.

You must also consider that your eyes and brain will adapt to what you are used to (your internal monitor).

I switched it from the "VS248" profile it was on to the generic "sRGB IEC61966-2.1" profile...

This only means the generic sRGB profile is closer to your existing monitor than the VS248 profile. It doesn't lead to any conclusion about which is more accurate.

The only way to know for sure which is more accurate is to either:

• Use a colorimeter to measure the accuracy of both monitor's output

Or

• View the same images on a monitor/computer system that has been recently calibrated and profiled using an accurate colorimeter and is also viewed in a standardized viewing environment.