iPhone XS True Tone: how to get rid of the yellow hue
Basically, with True Tone on, your device will use its sensors to analyze the ambient light around you. Then, it will do minor adjustments to its display's color and whitepoint calibration, making for a more natural viewing experience.
And we have enjoyed True Tone a lot — both on the iPad Pros and the iPhone 8 and iPhone 8 Plus, it looks great and we much prefer to keep it on. However, with the iPhone X, iPhone XS, and iPhone XS Max, True Tone gives the screen a very prominent, yellow-ish hue. It doesn't do nearly as good of a job as older models and, in fact, looks more like Night Shift (the feature that makes your display look warmer past-sundown). Still, on the iPhone XR, which is also a new generation iPhone model, True Tone looks as good as ever.
So, what gives?
Now, we are not Apple engineers or anything, but we can do some speculating and educated guessing. As you probably have heard, the new age iPhones — iPhone X, iPhone XS, and iPhone XS Max — are Apple's first handsets to have an OLED screen, as opposed to the LCD panels it used before. More specifically, Samsung-made OLED screens, and — even more specifically — Diamond PenTile matrix OLED panels. The iPhone XR, on the other hand, still uses LCD technology (Liquid Retina, Apple calls it).
Why is this important?
In classic LCD screens, a single pixel is made up of three sub-pixels — one red, one green, and one blue (RGB, eh?). Each pixel achieves its target color by combining the lights from its three sub-pixels.
The Diamond PenTile OLED panel doesn't have your classic RGB pixels. Instead, it's entirely covered by sub-pixels, spread across in a diagonal, diamond-shaped pattern. And, most importantly, their order goes red-green-blue-green (RGBG).
In other words:
There are a lot more green subpixels than typical
So, it's safe to say it might take Apple a while to nail the whitepoint as good as it did with the old LCD panels. Especially when it comes to a feature like True Tone that's supposed to dynamically calibrate colors on the fly. It actually took Samsung some time with its own phones, too, as its displays used to be too cold, then too greenish, and then started to hit the sweet spot around the Galaxy Note 5 era.
But let's get back to why we are here in the first place — can you make the True Tone setting on your iPhone X, iPhone XS, or iPhone XS Max actually look good?
Well yes, you can.
It does require a steady finger, an optional reference monitor, and the willingness to tinker. What we are going to do is we are going to activate a color filter from the phone's settings and tune it to our liking. Here goes:
First, make sure True Tone is on. You can do that either by going into Settings → Display, or simply by force-touching the brightness bar in the control center. Now that we've got that yellowy goodness on, let's see what we can do to fix it up.
Go into Settings → General → Accessibility → Display Accommodations → Color Filters
This menu is originally intended to add accessibility options for users that suffer from color blindness. However, check out the bottom-most option — the one called Color Tint. This allows you to apply a color filter over your display and adjust its intensity.
Naturally, we will keep the Intensity slider all the way down to 0. Then, we need to find the right Hue setting.
It helps to have a reference screen nearby — a computer monitor or another phone, which you trust for being a bit more accurate. If you are using one, open up a page with a white background on the reference monitor, and compare it to the whites on the iPhone you are currently tweaking while moving the Hue bar around.
The sweet spot for us is shown in the screenshots below — on both the iPhone XS and iPhone XS Max, it's near the right edge of the home bar. The yellow colors are subdued and give way to some blues with a hint of magenta.
Now, if you turn True Tone off, you will be greeted by an unpleasantly cold and blue-ish display. However, keep the feature on at all times and it'll balance itself out with your new color filter.