Science of the true color

I never saw a red color on the monitor until 2010. I spent most of my life thinking that a red stroke I painted in photoshop or a red shader I tweaked in a renderer were of the red color. I didn’t question a color sampler, if the sampler showed the values of red, for me it meant that I looked at the red color. But the ugly truth was that I never saw it.

In real life conditions, it is hard to find a 100% pure color. Even if somehow someone manages to print a pure primary color it would always have a different color response under different lighting and environment conditions. Given that, I had nothing to compare to. My idea of a pure red color was vague until we upgraded to a digital reference monitor and an industrial grade non-contact colorimeter. Each device costed a five figure amount of dollars and was designed for color critical work. It took two days to profile and calibrate the equipment. Once the calibration was over, I was about to see the truth, it was kind of a miracle for me back then. We had two monitors side to side: the reference grading monitor and prosumer LCD display. Each device received the same video signal of solid colors. The color asymmetry of two monitors was dramatic especially in reds and oranges. Looking at the differences, I realized that the color I thought was red in reality was orange and the real red displayed on the reference monitor was… so deep and infinite that it looked like an ocean of blood. If you ever find yourself in a dark room with a calibrated monitor don’t look at the red screen! The pure red color has some weird psychological impact.

The color accuracy is very important. The ranges of red and yellow are especially important because those are the colors responsible for skin tones. The accuracy of the green and blue aren’t so critical. For example, a slight color shift in the blue sky and foliage won’t be perceived as an error, while even a saddle inaccuracy in the skin tone may create an unbalanced look of a talent. It extremely important to establish a solid WYSIWYG (What You See Is What You Get) pipeline in any color workflow. It is a hard concept to grasp. It took me several weeks to fully understand the concept behind the digital color, the display output color and what we actually see in the end.

There is a myth notion that calibration utilities may actually fix the color accuracy of a display. That is not true to an extent. If a monitor can’t display a certain part of the gamut there is no software which would alter physical properties of the display panel. Some color issues like color balance and gamma can be fixed and aligned to the standards of sRGB and Rec709 given that the display has controls for tweaking or a LUT support. The reason I never saw the red color was because there were very few prosumer displays which could decently cover the gamut of Rec709, and there were no prosumer displays which supported the standard gamut of DCI-P3 (Digital Cinema).

Here is a little simulation of the problem.

color-display-comparison

I balanced the image on my laptop and once I was satisfied with colors, I viewed it on a reference monitor. Everything I’ve done was off. This is what happens when working on a low quality display.

The next image is a simulation of a color I thought was the red color. Note: The red on the right side is probably reddish-orange on most regular consumer displays.

color-gamut

Down below is a measured gamut of a display which has all kinds of inaccuracies and most importantly it would never be able to display the true red and blue colors. Moreover, the display has a strong color shift towards green in the range of skin tones. That means that an artist working on that kind of a monitor would always try to take out the green by adding red or magenta. But once the image is brought to a more accurate display or a cinema projector it would look oversaturated and reddish as the colors that were invisible or shifted would become evident.

monitor-gamut

The screenshot of LightSpace CMS a color management system I use at work.

The next image is a measurement of a good monitor which covers sRGB standard fairly well but has wrong white balance. The monitor would display everything warmer and more yellow. Obviously, an artist working on this monitor would balance the warmness by adding more blue to a picture. Once the finished work is displayed on other devices it would look too blue and cold. The same counts for gamma and brightness.

white-balance-monitor

Electronic manufacturers put all of their efforts in doubling pixel counts and making the sharpest and toxically saturated displays possible. Pixels are easy to quantify and label with marketing tags like 4k, Ultra HD, 8k etc. The color science and color fidelity, on the other hand, is kind of hard to sell. Who wants to deal with weird standards like rec709, DCI-P3 or ACES? While color features don’t get a lot of buzz, those are the most important elements in a professional production environment.

color-probes

Some of the tools used for professional calibration

As we’ve seen above, it is easy to get misguided by unmanaged displays. Consumer displays (even expensive ones) have all sorts of weird inaccuracies. And there isn’t much we can do about it unless there is a budget of 1K dollars per 1k pixels(do you see the marketing quantification?). Nevertheless, it is always good to be aware of these problems and know the color standards which would eventually guide you to a better fidelity products in the future.

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