Grayscale: Why White Is The Color Of Everything
The one calibration control that every monitor has is color temperature. And to alleviate any confusion over terminology right now, let’s establish that color temperature, grayscale, white balance, and white point are all the same thing.
Fixed-pixel displays produce color, and white, using red, green, and blue sub-pixels. How does white come from that? Let’s look at the CIE chart to find out.
This is the CIE chart we use in our monitor reviews. The square inside the gamut triangle represents the white point, where the three primary colors combine to produce white. Of course, the color of white is open to interpretation and that’s where we need to apply a standard. For the purposes of video and computer imaging, that standard is a color temperature of 6500 kelvins or D65.
Where did this value come from? 6500 K is the approximate color temperature of the mid-day sun, and white objects viewed under this light will take on a particular color. You can try this yourself by taking a piece of white paper and viewing it under different kinds of light. Fluorescent lighting looks a little green, while tungsten appears orange or yellow. And even sunlight at different times of day will change your perception of white.
Of course color temperature doesn’t just apply to white. For the purposes of calibration it does, but think about how lighting affects the color of any object. Remember the last time you bought paint for your home and it looked different in the store than it did on your wall? The color temperature of the light shining on that paint can drastically alter your perceptions.
So what happens when you adjust the color temp on your monitor? While we are only adjusting the white point, this procedure has an additional benefit. Correcting a display’s color temperature also aligns the secondary colors (cyan, magenta, and yellow) more closely to their targets.
It may be a little hard to see in the photo below, but look closely at cyan and magenta.
All we did to this monitor was correct the color temp from its default state to D65. You can see that cyan and magenta are now much closer to their targets than before. Why is yellow not affected? That is an anomaly of this particular monitor, an AOC Q2963PM. It’s not a flaw. It’s just the way that screen reacts to calibration.
Let’s bring Gavin out again. Here is the unedited shot for reference.
This is typical stage lighting that gives a natural and even look to the performer. Notice that the all-important flesh tones look exactly as they should.
Now we’ll make the color temp too warm; in other words, below D65.
This is done by editing the color balance in Photoshop. We simply turned up the red as one would do with the red slider on their monitor. It looks as if a red filter has been placed over the spotlight. It doesn’t look awful, but it’s not what we saw at the concert, is it?
Here’s the effect of having too much green.
Gavin looks very unnatural here. Green is the most obvious kind of error because the human eye is more sensitive to that color than any other. We doubt anyone would want their photos to look this way on purpose.
The last example shows the most common color temperature error.
This doesn’t look too bad, right? That’s because blue makes things appear brighter. Again, this is science coming into play. If your display is going to be off, blue errors impact image quality less severely than red or green. If you look at our monitor reviews, almost all screens measure a little too blue out of the box.
We have our feet wet with color adjustment via the RGB controls and white point. Now let’s look at color gamuts and how they’re implemented and measured.